I think it's something that would change person to person. This is all anecdotal, so it may be completely different for other people!0 When I went on a 5 week road trip through the US, all it took was a few laps around the block to get used to it for me. But I was definitely had to be very aware of keeping to the right at first. Having control on the 'wrong' side of the car is a bit tricky. (Especially in a Chevy Tahoe... Good Lord those things are huge...) Very unnerving feeling at first. But I think by day two or three I was pretty comfortable. The only thing that gave me grief was those crazy four-way stops. And some of the crazier highways. Girlfriend had to take over through Utah.
Two or three days seems really quick for anyone. But definitely it would vary by person. I was surprised it never clicked in for me in weeks. Getting hit by a car on the bike (in a parking lot, no big deal) a week or so in probably made me much more self-conscious about it though. Sounds like a great trip.
Huh, maybe I'm just a better driver than I thought :P I did do a bit of quad riding in Santorini as well... So I guess I wasn't going in completely blind... Getting hit by cars is never fun! And yeah, that'd definitely make me think twice about getting back into it! But I'm sure all it will take is practice. You'll get the hang of it in no time!