Typically you use all three at one time for maximum burst, and unless you have really fast fingers, it will take longer than 1.5 seconds.
I use a razer naga and have those three bound to the bottom row of buttons so I can just roll my thumb. Probably takes me half a second to fire them all up. Shift + that row does my wz heal/adrenaline rush/medpack so it hits whatever healing I have up at the time. I could probably macro each of those rows into one button if I better understood my own mouse, lmao.
Am I a scrub for "abusing" the "bug" of sticky grenade being affected by Pulse Generator?
Considering we don't have the 70% slow working, I certainly abuse the hell out of the extra AoE boost. Build a 5 stack, blow CDS, toss a sticky, HtL, MV and PC. That'll take up to 5 enemies from full to damn near dead and it will probably kill at least a couple of them.
My sentinel guildie was charging ahead of me to stop 4 enemies from capping in Novare. He leapt in figuring it was a suicide to buy time and then he sees all the enemy health dropping fast. He assumed the cavalry had arrived behind him as all 4 of them died, but no, it was just me. That has been my favorite pvp moment since I went Tactics.