You wouldn't have to pee a lot after 3 days. You can test as soon as your are late for your period. So on the 25th if you don't have your period, test for it.
My advice is to carry your own rubbers. Do not .E.V.E.R have sex with a man without a condom.
I would also advise you to go get yourself checked for stds because they are very real and can be very deadly - or a real pain to have to deal with for the rest of your life (like herpes! Or warts!). And, no, you wouldn't necessarily know if he had them - and he might not know either.
Be good to you, don't let anyone touch you without protecting yourself.