You can request upfront rent with an application to separate out the serious applicants and prevent you from wasting your time with someone who is simultaneously looking at many other listings. How much you ask for is up to you, but suggest at least half of the monthly rent payment. You can edit this from your conversation dashboard.
Upfront rent is always held in escrow by Flip until your lease begins, when the funds will be automatically applied towards your first month of rent.
If you requested that a renter put down the total amount of the lease (for example, $6,000 for a 3 month lease with monthly rent of $2,000) then it will be paid out to you at monthly intervals throughout the lease.