So if I get the job should I come out to them on the first day if they won't let me wear the mens uniform?
It's a total shame that our school waste time on teaching crap like abstinence and DARE when they ought to be teaching stuff like employment laws and employment realities.
First - Most jobs come with some like 90 day period of no-fail termination. Being, if they - for any reason, and they don't need to state one - don't want you to continue (not suited, too much trouble, they just don't like you) then they can end it then and there.
Second, depending on your state, if it's 'right to work', it's also 'right to fire'. Most jobs anymore at 'at will' contracts anyway, meaning they don't need a reason to fire you.
Even in places with very strong trans protection laws, you pretty much have to have your ducks in a row first. No legal marker change? Then they have no reason to accommodate you, and perhaps have legal grounds not to. Like the difference between a guy in a dress vs. a fully transitioned woman.
The system more than likely have you as F until you legally change it. "Coming out" is not enough, but perhaps 'being in treatment' is. Make sure you know exactly what the policy is.
And if they have such a policy, failure to disclose at the interview might be a deal-breaker.