This is our first year with a "real boat" and dealing with Fraser launches, crowds, etc. A few words to the wise from things I have learned...
Probably best to take your new boat to the LAKE first before you head to the river. Best to get any logistical issues sorted out with loading, unloading or whatever here than on the mighty Fraser.
Once reasonably comfortable with your new pleasure craft, head to the river. We like to launch at Island 22, however it is pretty far from the mouth of the Vedder so lately we have been launching in the Sumas Canal.
As others have said have a routine and stick to it. For us it's pull in near the launch and ready the boat and trailer. Undo straps, put plug in, put any rods and crap from truck in the boat. Once ready wife backs the boat down and I stay in it. When motor is just deep enough I yell stop and start it up. Then turn it off.
If I'm going to drive it off the trailer I won't kill the motor, instead will get the wife to back of the winch strap and unclip boat, then I'll drive it off under power. However we have generally been just attaching a rope to the bow, pushing it off the trailer, then pulling it to shore. It's only a 16ft boat so this is not that hard for me. With a bigger boat may not work. Then everyone hops in, me last and I push off as I hop in the bow. If it's shallow/mucky we'll row out a bit before I start the motor.
A few other random thoughts....aside from some tools and common sense stuff like that I carry 5L of extra gas under the passenger seat - you never know when you or someone else might need it. Also carry some jumper cables. Considering buying a power pack in case it is us that has the dead battery and noone is around to jumpstart us. Have some other random odds and ends in a tupperware that should allow me to handle most situations.