Tend to start mine going in late Feb, in beakers above a radiator in kitchen window (floor to ceiling window facing west-ish for as much sun as possible later). Kind of a guess so that once they have leaves there’s lots of spring time Sun.
Decent sized pots once established. Mine are just sat in a saucer.
Lemon Drop ones this year were ace. Nice flavour mid summer crop.
Habaneros seem to take much longer to germinate, and mine seem to start flowering at end of August.
Got most of my seeds from Seaspring Seeds, whose website does state how tall and wide most varieties of plants grow. My Habs usually end up ridiculously wide for a window. Lemon drop was taller, but less wide, so just needed a stake. Prairie Fire, small and bushy, but flavour not as good as habaneros (imho).
White flies and aphids have been a problem.
Have a friend in California, and another in Oklahoma, who both grow Habaneros and Trinidads, and they get way way more crop and months earlier too.