I'm on a compounded cream. I'm not sure if the absorption rate between the cream and gel is different, but based on stuff I've read the minimum to wait before doing anything that'll make you sweat a lot is 2 hours. As far as getting wet (shower, swimming) the minimum is 4 hours. As a rule of thumb, though, I wait at least 6 hours before showering just in case.
To get a more definite answer, though, you should be able to just call the pharmacy to ask.