It really depends on two things.
how backed up is GMAC with foreclosures,
two are you going to attempt a short sale or is it in your mind that your going to f/c,
no fight whatsoever and three,
just how far behind are you.
If you havn`t missed any payments yet,
you have a long road to go.
If you have missed payments,
you should started getting the phone calls.
If your mind is set and your letting the property go (keep in mind with a f/c,
financing will be difficult for the next 3-5 years,
and it will stay on your record for at least 7)
you`ll want to pay attention to the f/c attorney letters and phone calls,
they will let you know when your date is set