Got it. I thought you were going to use it in the hive that was raising a new queen. I second what Coal Reaper suggested, treat before hand. Last year we had a late spring and didn't see drones here along the Wasatch front until mid May. This year spring looks to be about three or four weeks ahead of where we were last year. Make sure you are seeing drones before you make the split.I would start around mid april and I don't think it would get too hot in the next two weeks.