The idea that the only way a negative could stick would be for a no-call, no-show after a deal what is agreed to with an exact meeting time and place was surprising to me when I first joined the site.
But apparently it has been the rule for a very long time.
In the law, a contract can be legally binding as soon as you have a bare minimum of the terms and conditions agreed to, and both parties say yes (or the party accepting the offer says yes-- the person who made the offer doesn't have to say "yes" because the other person can make it binding just by accepting it).
there's no need for the exact time and date of the transfer to make a valid contract
There has to be a reasonable time frame in place though. Otherwise you could never force the other party to act on the contract.