Can I mail my 90-day reporting documents before the 15-day prestart period begins?

The user is inquiring whether they can mail their 90-day reporting documents ahead of the 15-day prestart period, which starts next Monday, or if they should wait until the designated time. They clarified that the prestart period allows submission from 15 days before the due date to one week after, but are unsure if mailing a week before the start is acceptable.