Do we have to sign the contract before receiving the deposit and advance rent

Tenancy Types and Management

Hello, I am setting up an AST with a couple who are paying 6 months rent in advance as well as a deposit, due to a poor credit record. Can I ask to receive all the monies due before signing a contract with them in person on move in day? I'm nervous about using an electronic signature and would rather do everything on the day - sign the AST, which they have already had sight of, with a wet signature, inventory, schedule of condition, guarantor form, addendum to AST which stated that they need to pay 6 months in advance, and hand over the keys. Obviously to do that I need to ensure that I have receipt of the money. They want me to sign the contract before sending me the money. Should we do 'pay the deposit, sign the contract, receive advance rental then hand over keys', or am I able to say 'pay the deposit and advance rental first, then sign the contract in person and then I'll hand over the keys? With thanks in anticipation