I've found it best to suck the whole bottle down, but do it in a "measured" way so you don't hydrolock the motor! If it's accessible, I'd take the entire PCV hose off and get a long length of hose, attach to the fitting on the intake manifold, and poor the cleaner in a dish or bowl so you can see how much your sucking up. I just place the bowl on the radiator shroud or something. It's easier to do it this way if someone is modulating the throttle for you as it'll want to die. It'll for sure die if you just jam the hose in the bottle and let it suck the whole thing in one shot.
Do it on a hot engine, let it sit for an hour or two, then take it for a spirited drive and rid your neighborhood of skeeters!