Well then, no, there's no benefit to paying early. :P
Not really, have done it a couple of times, as I've got a ton of games coming this & next month and wanted to spread the financial cost over a couple of payslips etc... So ended up paying early for Batman, AC: Revelations etc...
I think it'll be best to use the pay now. That way the payments out the way and you can see how much money you got left. If you leave it to take the money before dispatch, you might of spent into some of the price for the game. leaving you overdrawn or not
getting it on time if they are declined. But if you know your gonna have the money in then makes no difference.