stage 1: progenitor
"Stage 1 will be move at a breakneck speed. This will be the buggiest and busiest stage of the beta. A bunch of unfinished features will be disabled whilst we finish them up. Updates will come thick and fast, sometimes as often as multiple updates a day.
If you choose to take part during stage 1 you should expect bugs, lots of balance changes, you shouldnât get too attached to your character or universe as we may make changes that require you to start from...

I'm definitely gonna try it out a bunch during stage one, but once stage two is out, I'm gonna play it heavily. I don't really wanna wait for stage three because I'm already pretty used to buggy/unfinished games.
That sounds like a good plan. I don't want to spend lots of time and lose a save. Odd thing though, I haven't really gone back to my old Terraria characters... but having them around is really awesome for historical reasons. Having the option is nice and still having access to my first world is pretty great too. So, yeah, that would hold me back from diving in hard at first.