Steve - leaving the halides off for a couple of days might help for sure. If you see a die off, then be sure to really siphon to get it out of the tank.
I thought the recommended water change when switching salts was 5%, but I can't say for sure. Maybe try a 5% water change, and see how everything looks. As with any water change, make sure your salinity and temperature matches, and you let it mix for 24 hours or so.
Let us know how the "lights off" works out.