V.B.
At some point, when you're comfortable that he knows what he's doing and can tell you a little bit ahead of time, you just have to do it and carry around extra clothes for the accidents. You can keep a little potty in the back of your car if you want (I have never done this, but know people who have) so that you can just pull over and let them go in that (or if you're at the park, etc. where there may not be a potty handy). They also sell foldable, portable potty seats (I think I got it at Babies R Us) so that you can keep it in your purse to use when you're out (It comes with a case to put it in). They also make little covers that you can put in their car seats (I think it's called a piddle pad) so that if they have an accident in the car, you don't have to clean the whole car seat cover. Anyway, those are just a few of the conveniences they have to make the transition easier, but with my son (who is also only potty trained a few weeks), we just went for the gusto (I use the piddle pad, but that's it). He is my second though....with my daughter I carried around the portable seat. Not so much with him. Good luck!