Ask before accepting if the start date is important to your decision.

Start dates are often more flexible than core compensation, but the amount of flexibility depends on onboarding classes, office needs and role type.

Frame the request around the date you can realistically start, not around testing how much leverage you have. A clear reason and a specific alternative are easier for recruiting to evaluate.

Do not assume a later date is guaranteed until it is confirmed. If the firm agrees, get the revised timing documented with the rest of the offer details before you rely on it.

I moved mine by a month before accepting. Recruiting just checked which onboarding class could take me.

I would definitely raise it before signing if the date affects whether you can actually take the offer.

I'd probably focus on the practical decision here rather than trying to decode a hidden signal. The part about can i negotiate my consulting start date before accepting the offer is what I'd want to clarify first.