You may prepay your loan at any time, without penalty. By prepaying your loan, you may reduce the amount of your total obligation and reduce the length of your repayment period thereby decreasing the total amount of interest you pay.

Unless you request otherwise, your payments will be applied to:

First it's applied to accrued late charges and collection costs.
Second it's applied to accrued interest.
Third it's applied to principal owed.

Your next scheduled payment would be due on the usual date for the usual amount.