It depends on two things;
a) How long the sending bank takes to enter the SWIFT instructions
b) How long the receiving bank takes to process the SWIFT instructions
The method that banks use to actually 'send' the transfer is just an electronic message saying 'hey, credit $x to this account, we'll pay you later', and the receiving bank doesn't actually wait to receive the cold hard cash before crediting the account - they credit the account upon receiving the instruction, which takes literally only a few moments from being entered by the sending bank.