If this just happened it will be a couple of days at least before hunger starts taking over the excitement of exploring a whole new world.

Hopefully he will be back soon, cats bond to places more than people so if he gets scared his instinct will be to return home. Just be patient, give it at least 5 days before giving up on the traps.

Feel for you buddy, I just got a kitten a month ago. Will let them out into the garden eventually but not before vaccinations and neutering. So I am also paranoid about cat getting out before then and he's already got out once but thankfully I could pick him up and bring him back inside.

Hope the little bugger comes back soon.