Final Invoice normally issued at least 7 days before collection.
If your account does not change status to "Paid" (i.e. your payment is showing on your account) then before you set off for collection clear the payment with delivery_GB - by providing proof of payment (they may ask for more / different info). Once they are happy then in effect the Collection Staff will see your car as "Paid" and just hand you the keys (worth taking proof of payment with you, but I'll eat my hat if you need it). If you haven't done the above the process at collection may well be protracted, at the least (and you will be holding everyone else up ... time allocated for handover is probably less than an Amazon warehouse picker ...)
Note that your bank may have a limit on how much you can transfer, so £50K at, say, £10K per day ... needs some time.
I have paid 15:00 for collection at 09:00 following day (multiple repeated mistakes on preparing a Final Invoice for me) but I don't recommend it!