Each dog is going to very of course. I would say probably in the neighborhood of 7 to 10 days. Definitely make sure that they get each part and understand what your asking before moving on. Some trainers start on pattern blinds when the dogs are about 80% done with swim by.
Swimby can take anywhere from 4 days for a few very special dogs, to 2 weeks, with the average dog being close to 10-12 days or so. Once you get the overs both ways in the same pond, it is best to stop in that pond and repeat in at least 2 different ponds to enforce what has been learned.
It's one thing to do it, it's another to have it "polished" and "ingrained". For me the average would be around 7-10 day's, don't weant to screw that one up by pushing past it before it's completly done.