Grabbing is pretty instant, as you will notice when it goes where it shouldn't. I would just look at the instructions on the tube before buying for the actual drying time, but like most adhesives, the longer you can give it before trying to move the glued item, the better.
Like I said, mine was a second hand one - I've never had any trouble in that area. Just as well - the fin doesn't want to come out of the fin box anyway, if I really need to shift it I might have some trouble there.
Anything else?
It did seem to collect some water, this eventually turned out to be a minor leak at the base of the rudder tube (the joys of second hand!). I had to cut a hatch in the rear deck to get access, give a generous smear of silicone rubber stuff in the affected area, and make a new cover from a bit of styrene sheet, a bit bigger than the hole, fixed with the silicone rubber, in the expectation that should I ever need access again, it will be an easy job to remove it. It was probably this ingress of water that weakened the original glue.
I fitted a leech line on the jib as well. It helps keep the jib in shape by completing the triangle formed by the luff line up the front, the boom across the bottom and then the leech at the back.