You are correct- you will preclear Customs on the morning that you depart for Orlando. You would want to have you ME tags on the bags at that time. No need to do it in Edmonton and risk having them torn off accidentally.
Check in with the airline is straightforward. Have your preprinted boarding pass ready. Use the machines to print out your baggage tags. Then get in line for the counter. Follow the instructions on where to go to preclear Customs. (NOTE: you have to go directly from checkin to Customs. No detouring). Once through Customs it's the same as any other flight.