What airline are you traveling (so we can give you specific hints)? Also, what are your flight times (arrival in Toronto, and Toronto departure)? Finally, what day of the week?
Clearing customs in Toronto is not difficult. It's taken me (without using my trusted traveller pre-clearance) anywhere from 10 minutes to 45 minutes.
Generically:
1) get off your flight in Toronto
2) walk through the airport, leaving the secure area to get your baggage (yes, your luggage was checked through to Florida at your originating airport, but all travellers must physically carry their own bags through US Customs). Follow the signs to the USA Customs clearance area (by memory, I think you'll see overhead signs that have an American flag).
3) near the US Customs area, they'll be a special luggage carousel for people who are connecting to a USA departure flight (do not go to the "normal" baggage carousel -- go to the carousel by USA customs).
4) get a luggage cart (easiest method is to pay by credit card), to assist in moving your luggage
5) take your luggage off the carousel (it'll probably take 20 - 30 minutes after the plane arrives, before your luggage will be available on this carousel).
6) walk to the US Customs area. Enroute to this area, you will need to fill out the US Customs forms (one per family) - forms are available outside the Customs area -- bring your own pen....
7) Enter the US Customs area - showing your completed Customs form and boarding pass to the agent monitoring the door.
8) stand in queue for customs.
9) talk to US Customs agent - he/she will apply a ink stamp to your passport and UC Customs form, and hand both back to you
10) leave Customs area, taking your forms and baggage, and hand the form to another US agent as you leave the area.
11) place your baggage on a conveyor belt that is immediately after the US Customs area (you won't miss seeing it)
12) walk down a hallway, and re-clear security
13) sit down at departure gate and relax (or relax as much as possible with 2 small children).
It's less complex than it seems. Most of the steps above are very quick.
Happy travelling.