You will need to submit it at the time specified by that loan servicer.
While each of the loan servicers will take into account that you have other loans when calculating income-driven repayment amounts, you may not be able to submit the paperwork to your loan servicers at the same time.
Let's consider some arguments in favor of student loan consolidation and some arguments against student loan consolidation.
For more information, I recommend checking out the Department of Education’s website on student loan consolidation.
It depends in part on how your financial aid package was put together, as well as on how your loans have been assigned, bought and sold to other financial institutions.
When you receive a financial aid package, it usually includes awards, grants, and loans offered to you to help you pay for the cost of attendance.