I think I'd probably freak out. I mean, seriously, I just suddenly turn into the opposite gender, with no explanation why? I'd scream the place down. What the hell would prompt that sort of thing? What implications would it have on my health going forward? I expect my first few hours would be mindless panic.
I think I'd have a hard time adjusting biologically. After all, girls and boys have different toys, and getting adjusted to the physical changes would probably be quite difficult. Psychologically, once I'd calmed down a little I'd probably adjust pretty quickly - gender is a physical thing only for me; I don't identify as male or female and that wouldn't change - but yeah, I don't think anyone would be able to just have it immediately click in that sense. Not all at once.
