I start mine on my kitchen window sill. Once they pop, I put them outside within 2 to 3 days to keep from stretching. They are out there for another week or so, then I transfer them to their final place, 10 gallon pots. Works well for me.
Wish id learned about hardening off before i put my 18 month old reaper plants outside last summer. 2 days man. How the fuck does 2 days of being outside in like 15*c kill an 18 month old plant? Almost cried lol.
I've fucked up a few plants due to not hardening off and I still don't put as much effort into it as I should.