We had the pool company open today since it was included in the original deal. I got home and dropped in the hose. One thing they did not mention to me is the process used to switch the suction from the main drain to the skimmer. I know which lever to move, and to where, just not sure if I need to turn the pump off first, or any other required steps. Is there a certain time period I should wait before activating the skimmer? Thanks.