Low keys are PERFECT for learning. You can focus on mechanics more than doing DPS, and if you mess up you don’t wipe or die from it. You can stop, read debuffs, pay attention to timers and casts/abilities, and really just do mechanics. At the higher levels executing mechanics properly neutralizes the need for healing quite a bit. Same goes for dungeon mobs, if they even remotely hurt on a +0 level, they will start to hurt when you hit the 12s range, so learning early to get stops in is good.
I’d practice general rotation and mechanics in 0s first, then move into 2s to practice routes and percent count.
GLHF!
IMO you practice rotations and that stuff outside of a dungeon on a dummy. If you get into an M0 or a 2-3 key, it’s best to watch the dungeon very closely and flawlessly execute mechanics. Once scaling hits in higher keys, you die if you don’t play correctly. Too many people focus on DPS, healing etc, when doing mechanics makes all of the difference.
Keys up to +5 are so easy, there’s no real checks in them anyway, and this late in the season especially, you totally out gear stuff.
Well yes, obviously this is the first step. If you have just swapped to the new spec and have nothing set up, no idea how to play it, hit a dummy first. Once your keybinds are set up and you are vaguely familiar with what to do, get into those base 0s!