Short-term role before MBB start - take it or decline

Personally, I would advise against taking the boutique role for three reasons:

• Professional courtesy: Reneging or leaving early places a significant burden on the firm, as they will have to restart their recruiting process to fill the gap.
• Marginal utility of experience: While the experience would be valuable, the technical skills (Excel, slide design, storylining) can be self-taught or learned during your main stint. The trade-off isn't worth it.
• Reputational risk: At least to me, leaving after 2-3 months doesn't look good. The consulting world is incredibly small. Protecting your professional brand is crucial, and you never know when burning a bridge might come back to haunt you

This is a great problem to have, and it’s smart that you’re thinking about the reputational component now. Here is the insider view: you should absolutely take the boutique role.

The reputational risk is significantly lower than you perceive, especially given the context. First, the boutique already delayed your start date by eight months. They know you are an entry-level candidate who was actively recruiting during that unexpected gap, and they know the caliber of candidates they are hiring are likely applying to MBB. It’s a transaction. They need short-term capacity; you need experience. If you leave cleanly after three months for a firm that is considered a tier above, they will not be shocked or hold a significant grudge. They just won't.

The upside of the short stint far outweighs the minimal risk. Three months is enough time to develop critical, transferable muscle memory: how to structure a presentation, manage an administrative assistant, communicate with a Partner, and survive a project team environment. This is invaluable exposure that makes your first six months at MBB much less stressful. You will effectively be spending 90 days getting paid to learn the basics before starting the real career climb.

To manage the exit cleanly, do not wait until your one-month notice period. Frame the move proactively. Tell the boutique senior leadership immediately after Christmas or in early January (four to five months out from the MBB start) that you were offered a deferred start at one of the "Big Three" last year, and that date has finally materialized in May. Explain that while you are grateful for the boutique offer and committed to the Feb–May timeframe, you need to honor the prior commitment. This gives them maximum runway to staff and backfill. Be apologetic, professional, and offer to train your replacement. You will be burning zero bridges this way.

Hope it helps!

Wait. 

You're not going to enjoy the transition. 

They are not going to enjoy having somebody ramp up for 2 months and then leaving when they're starting to be useful.

On your CV it's going to look plain confusing.

The only possible reason I would think it's worth doing it is to be protected against the risk of MBB moving your starting data (which is rather unlikely).

Congrats for the offer, btw!

And if you're starting soon in consulting, you might find this guide useful:

• Expert Guide: How to Become A Distinctive Consultant

Best,

Cristian

Here’s how I will break down the decision process, if I were you.

1. What’s the real risk of joining for 2–3 months and leaving?

Low. Lower than most candidates assume.

Context matters, and your context works in your favour:

• They deferred your start by ~8 months. That already signals volatility on their side, not yours.
• Firms know entry-level candidates continue recruiting when there’s a long gap.
• Moving to MBB is an understood, accepted upgrade. No boutique leader is shocked when a top candidate leaves for MBB.
• Consulting is transactional at the junior level. They need capacity; you need experience - both sides benefit short-term.

Handled well, this is not career-damaging.

2. What’s the upside of doing the boutique stint?

Material.

In 8–10 weeks, you’ll pick up early muscle memory that makes your first 3–6 months at MBB smoother:

• Structuring decks
• Working with Partners and Managers
• Managing workflow under pressure
• Real client exposure
• Understanding team norms
• Building basic consulting judgement

You walk into MBB “pre-ramped”, which reduces stress and increases your early performance ceiling.

And yes, you get paid while learning.

3. What are the downsides?

They’re real, but small and manageable:

• Short stint looks odd if left unexplained, but you will have a clean explanation (“start was deferred; joined to gain experience; honoured a prior commitment to MBB”).
• You’ll be barely useful by the time you leave, but that’s the firm’s staffing math to manage; not your responsibility.
• Some discomfort walking away quickly — but this is part of professional life, not a major reputational mark.

4. How to exit without burning a bridge

This is where the real game is won.

Tell them before you join; ideally early Jan:

• You had a deferred MBB start from last year
• You must honour that commitment in May
• You are grateful for the role
• You’re fully committed to delivering from Feb–May
• You want to give maximum notice to help them backfill

Be professional, appreciative, and transparent.
Do NOT spring the news on them after only 6 weeks on the job.

If you follow this script, you burn zero bridges.

5. So… should you take it?

If you manage the communication properly: Yes.

• The risk is small
• The upside is real
• The explanation is clean
• The boutique already shifted your timeline
• MBB will not care either way

The only scenario where I would say “don’t join” is if you want a quiet, restful runway before starting MBB.

But from a skill-building and signalling standpoint, joining is net-positive.

Bottom line

There is no meaningful reputational risk if you’re transparent early and exit professionally.
The stint will help you more than it harms you.