File the forebearance immediately, and speak with someone at Sallie Mae to see if they can reage the June payment. If you aren't 30 days past due yet, you should be okay. Typically you can also file a forbearance through their website which usually processes faster in my experience.
Starting Score LENDER PULLS (02/23/10): 587 (TU) 554 (EQ) 562 (EX) 
@SharonNYU wrote:
I have just completed my 2 year degree in May and will start my 4 year degree in September. I did not realize that my school loans would be due in June and have not paid the amounts due ($330). I can not register for the Fall until August. I've contacted Sallie Mae and they provided me with a forebearance until October. How will this affect my credit score?
I read your post and something seems a bit off. is this a federal student loan? The reason i ask is because with federal student loans, you normally have a 6 month grace period before you have to start making payments (unless you have already used this grace period). When did you stop becoming at least a half time student? And are we talking about May 2010 and then your payment was due in June 2010? We would need some additional information because if you are already registered into the 4 year college then most federal student loans do not count the summer term as a student having to go at least half term. You may want to read up on the information from the Department of Education's website because if your loans should still be in deferment because of school, I personally would prefer that show up rather than a forebearance. Not sure if the forebearance will actually affect your score.
@SharonNYU wrote:Yes, this is for federal loans and all the months I referred to are for 2010. I'm enrolled in 4 year school (NYU) but was registered for my 2 year degree. In May 2010 I completed this degree and in September 2010 I will begin my 4 year degree program. I too thought there would be a 6 month grace period. I will check with Sallie Mae to confirm.
Yes, please do because if you were enrolled at least half time and went right from your 2 year degree to going for your 4 year degree, then those student loans should have still been in a deferred status because you are in school. Unless of course you requested to make payments while in school, or if this is some other type of student loan you have through Sallie Mae. But I would surely talk with them about your options. Also you may want to make sure that the forebareance is BEFORE that payment is due. If not, you may want to try to make the payment and then go from there. At least it will save you from having any bad marks on your credit. But definitely give them a call and see what they say. Not to sound shrewd, but you may even want to call more than once with the same questions to see if you get the same answers.
Have you spoke with Sallie Mae yet? I agree with Tazman that you should still be in deferment, or at least within your grace period.
Have you previously used all of your 6-month grace?
Did you successfully complete the previous semester? (ei, no withdrawal, incomplete, fails)
If, for some reason, you are exempted from deferment and grace, then you would most likely get a 30 day late showing on your credit report. Just make sure to call Sallie Mae to find out more.