Wait varies and it all depends, literally, on your check-in time since the guy who makes the class up dates goes in sequential order from the check-in log book. All my classmates from API reported earlier than me so they classed up the week after check-in in VT-28. I, on the other hand since I like to utilize my time off to the very last minute checked-in with another guy from API five hours after everyone else. We are scheduled to class-up two weeks after our check-in date with VT-27. Some guys, depending on how many API sends over class up that week. Monday, at least for the past two classes has been the last day to check-in. Check-in briefs have been taking place on Tuesday. Medical is minor, just some shots and blood work and that will all be done by Friday. You will have a checklist to complete such as Security pass & tag, register for piss test, check-in with house hold goods, ect ect.
But this is probably too much info for your purposes. Bottom-line: you will most likely have a week off if not two. 90% chance of a week, 9% of two weeks, and 1% that you will have no weeks off and jump right into it. Something else that you didn't want to hear probably...you will have watch. It is inescapable unlike stash jobs although they are sometimes hard to dodge. You will either have quarterdeck watch which is a 12 hr shift or CNATRA quarterdeck watch which is a work week consisting of a 6 hr shift from Monday-Friday. If you are unlucky, you will get both watches.
Take your girlfriend to downtown and to the Islands. I would stay away from northern Corpus if you haven't heard that already. Crime is pretty bad up there and there are several areas that Navy personnel are forbidden to visit.