Mastering Your First 90 Days as a Chief of Staff
Insights from our first Nova Chat of 2026
The first 90 days in a Chief of Staff role can feel like a lot. There's pressure to prove yourself, earn trust, understand the business, and (if you're transitioning from an EA role) completely rewire how you think about your work in service of your principal and their priorities. It's a big shift. And it's one worth doing thoughtfully.
In our first Nova Chat of 2026, Maggie sat down with Jillian Hufnagel and Courtney Vincent—two operators turned executive coaches and strategic advisors with deep experience supporting CEOs through growth, complexity, and high-stakes change—to unpack what it actually takes to set yourself up for success in your first three months as a Chief of Staff.
Think of It as Phases, Not a Sprint
One of the most important reframes we can offer new Chiefs of Staff? The first 90 days aren't about doing. They're about becoming.
In the early weeks, your job is to observe, listen, and build a clear understanding of how your principal operates and what they prioritize. As Jillian put it: "Read, watch, listen, ingest, sponge into it." That's the whole assignment.
If you're coming from an EA background, this transition also asks you to zoom out. Where EA work tends to be reactive and immediate, the CoS role requires you to look further ahead. Courtney described it this way: "When you shift into a Chief of Staff position, you are looking further out. You're thinking bigger-picture: Why are we spending time on the things we're spending our time on, and are they in service of the principal's vision?"
That shift from execution to strategy is what defines the role. And it starts on Day 1.
Trust Takes Time. There Are No Shortcuts
Trust is the foundation of everything a Chief of Staff does. Without it, you can't influence, you can't advise, and you can't lead on behalf of your principal. So how do you build it in the early days?
Listen actively and close the loop. When your principal or team members share something with you, reflect it back. Let them know what you heard, what you're planning to do with it, and why. Courtney's framing was spot-on: "This is what I think I might do as a result. Here's why I think I'm going to do that, and here's the problem it would solve. What do you think?" That simple habit signals that you're paying attention and operating with intention.
Do what you say you're going to do. Reliability is trust. Follow through, on time, every time. That's how credibility compounds.
Be curious about people. Trust isn't just built in the boardroom. It's built in the hallways, in casual check-ins, in knowing what someone's been working on outside of their title. Relationship-building starts with genuine curiosity and empathy.
This means understanding team dynamics, learning the history behind why processes exist, and approaching everything with patience. That's the work in the early days.
Document the Rhythm of Business Before You Touch It
Before you start changing anything, you need to understand how things actually run for your principal and what’s demanding their time. That means mapping the Rhythm of Business—the predictable, recurring activities that keep your leader and their business moving: weekly meetings, monthly reviews, quarterly planning cycles, annual priorities.
Think of the business like a human body, with interconnected systems. Before you intervene, you need a full picture of what's healthy, what's strained, and what might be holding things back.
Start with your principal's calendar. What are their recurring touchpoints? Where are they over-committed? What's missing from a strategic standpoint? Then use templates to visualize the rhythm across the full year through the lens of your leader’s priorities and decision-making load. Identify the heavy months, the gaps, and the misalignments.
The key instruction here is important: document first, change later. Once you understand the current state, you can align it to your leader's vision and start making smart recommendations that protect their time and give them leverage.
Small Wins Build Big Credibility
So when do you start doing more? When the team starts coming to you.
Jillian described this as a key signal. When your colleagues seek out your input and trust your judgment, that's your green light to take on more. And when you do, start small. Look for projects you can own from beginning to end and deliver them well. That's how you validate your credibility and quiet the imposter syndrome that almost every new Chief of Staff experiences.
Courtney's advice was simple and worth repeating: "Minimal, minimal, minimal. Do less, then pile on as you see the team shift and adapt."
If You're Transitioning from EA: Role Clarity Is Everything
For EAs stepping into a Chief of Staff role (especially with the same leader), the most important thing you can do is get clear on where one role ends and the other begins.
Jillian recommended creating a side-by-side responsibility chart: what's EA work, what's CoS work, and how do you transition out of the operational tasks over time? Color-coding helps. Honest conversations with your leader help even more.
The mindset shift matters, too. Moving from short-term task management to long-term strategic thinking can feel uncomfortable at first, and that's normal. Your prior experience as an EA is actually an asset here. You already understand the leader, the business, and the rhythm. Now you're just operating at a different altitude with a greater responsibility to shape how your leader spends their time and attention.
And a reminder worth noting: not every EA wants to become a Chief of Staff, and that's completely valid. There are plenty of ways to expand your expertise and increase your impact from within an EA capacity. Know what you want, and pursue it with intention.
Don't Over-Promise in the First 90 Days
This one's a common trap, especially in fast-moving startup environments where the pace is high and the pressure to contribute is immediate.
Taking on too much too soon, or saying yes to goals that are too vague and too big, can backfire quickly. Courtney shared a story from her own experience working with a fast-moving CEO whose early-stage directives were broad and undefined. Even though her individual contributions were strong, the lack of clear expectations made it hard to demonstrate impact. It's a credibility killer, as Jillian put it: "If you say yes but can't deliver on expectations, you've already started to lose."
Set clear expectations with your principal early. Agree on what success looks like in 30, 60, and 90 days. And communicate consistently along the way as it relates to supporting their priorities and reducing noise around them.
The Big Picture
The first 90 days are about curiosity before action, trust before influence, and a plan before execution. Here's the short version of everything we covered:
Listen, observe, and build trust before you try to change anything.
Document the Rhythm of Business in its current state before making a single recommendation.
Start small, deliver well, and let your credibility grow from there.
If you're transitioning from EA, create clarity around your new scope and shift your mindset to match it.
Set clear expectations early with your principal and with yourself.
You're listening and observing, then leaning in before action so that when you act, it directly advances your leader’s priorities and impact.
P.S. You can watch the full replay at https://www.novachiefofstaff.com/novacontent
Want to go deeper? Nova's Chief of Staff Certification course and our Rhythm of Business workshop give you the templates, frameworks, and community to put all of this into practice from Day 1. Get started at https://www.novachiefofstaff.com/