It shouldn’t really matter in which order you start the apps. The only two things that have to be running before launching a game are vorpX and your game launcher/store (Steam/Epic/Uplay etc.), order doesn’t matter.
SteamVR and the Mixed Reality Portal get launched automatically when vorpX initializes SteamVR, so you don’t necessarily have to launch them beforehand. Doesn’t hurt of course, but if the aren’t running, they should launch automatically.