Answers on acclimation time are all over the place, from very short (literally some people dump them right in) to extremely long (i.e., placing them in a QT and slowly raising the salinity over a period of 1-2 weeks).
Personally, I've had a lot of success with about 5 hours going from fresh to full salt. It's important to have a heater in with them, as they tend to stress easily if their water gets chilled, and I sometimes feed just a little about halfway through. I've had really good luck with that procedure, but I don't think there's any good objective work out there on what really works and what's least stressful for them physiologically. I monitor them the entire 5 hours, but try to keep the lights off and their bucket covered with an easily moved peephole to check in on them.