Once you are "separated" from your school, there is a grace period that begins before payments are due on your federal loans. How long that is depends on the type of loan. For Stafford loans it is 6 months; for Perkins loans it is 9 months. PLUS loans (Parent or Graduate) do not have a grace-period, but there is a 6-month deferment available to help line-up the start date for repayment.
Notice, however, that I said that the grace period runs from "separation" from your school, not "Graduation." This is because separation occurs at completion of a program or when enrollment falls below half time.
Half time is defined by the school, though, not the lender, since some schools use a 4 credit hour system while others use a 3 credit hour system. So if you drop out or go to one or two classes a semester, your lender can declare you "separated" and start the grace period running.
If you live in New Jersey and are concerned about how you will pay your federal student loan debt, I may be able to be of assistance. Just download this questionnaire, fill it out, and then fax it to me at 856-686-9911 or e-mail it to me. I will then review it to determine if I can be of assistance and contact you to discuss representation.