It takes up to a week or 10 days sometimes longer for it to clear but yeah you could do that and make sure the guy knows that you send nothing until it all checks out correctly. Let him know if he comes up short or rips you off you keep it all and report him to the service for bank fraud etc.

Also make sure you get his home address, phone number and place of employment that can be verified before signing the deal. If he says fuck you then tell him it is for your protection and this is just how things have to go or he can eat a bowl of dicks and scam someone else.