When it comes to late fees, the Submitted Date is the date that determines if a family is charged a late fee. As long as the family submits their payment before/on the payment due date or during the Grace Period (if your school has one), then the late fee will not be applied to the account. This is based on the payment being a successful payment as well. 

If an account is activated within 10 days of the due date, no follow up fee will apply for the month of activation. This is to allow the family time to make their payment without being penalized. The follow up service will resume for the subsequent months of the payment plan.