The key is to temporarily put the standard of living on hold for the first year. Obviously this is going to be different for each individual, but if I may add my $0.02:

1: Start now by changing QOL and by saving as much as you can. You may need to tap into savings the first year.

2: Expect to make some changes to lifestyle. Again, it will mean different things to different people, but this may mean eating in more and out less, putting off home improvements etc., etc. However, remember that it is only temporary.

3: This can be tied into step one, but take the opportunity now to pay off whatever you may owe to help you adjust to probationary pay.

Personally, I wouldn't tap into retirement funds because this may cost you more long-term. You might want to consider contributing less into a 401k temporarily while you save that money into an account that could possibly be used to help supplement your first year pay.

And remember, this is only a temporary lifestyle change until you finish your first year.