Hooking up a primed keg (possibly a stupid question)

OK, so soon I hope to have my keezer ready to go. I've got 4 kegs that have been primed (with a shot of gas added to pressurize the kegs at kegging time) and conditioning now for almost the full 3 weeks, and I'm starting to get a little anxious about the actual hooking them up. I figure they should be pretty well pressurized and I'm hoping to NOT have a bunch of beer shoot up into the gas lines, because I'd hate to have to clean that.
I figure step one is to actually leave the kegs in the keezer for a day or two to properly chill, then should I hook up to the "out" line first, and then attach the gas? Should I release pressure first? What do you guys do? I am most worried about my stout keg, which is very very very full.

 

Yes I do have check valves, so my regulator is safe. And yes, I realize that I am probably just being overly neurotic because I'm new to the kegging world.

 

Unless you overfilled the keg, the gas in dip tube should be far enough the beer that it won't backup into the gas line. I've never had check valves on mine and never had a problem. That isn't to say that check valves aren't a good idea, it is just not much of a worry IMHO.

 

I do believe I overfilled the stout keg.. the star san bubbles obscured how full it was getting... the others should be fine.

 

I always purge off the gas in the keg before hooking it up to the gas at serving pressure...