the title and question seem to e asking 2 different things.
no, you can't use instant deposit in Square for a check you accepted, only credit card transactions.
you can't use a checking account for instant deposit. It needs to be a debit card. checking accounts are linked for the free next business day deposit.
https://squareup.com/help/us/en/article/5405-set-up-and-manage-instant-deposits
