When to plant peppers depends on a lot of factors, many of which have already been touched on.
My last frost date is 5-1, andI start a few of those chinense peppers early, on 2-7, while I plant all the rest on 4-1, to be put out around 5-15. When planted that early, they have to be in larger pots than the later ones, so only about 8 can fit in a tray, rather than 32, as with the smaller, later varieties. If you have limited lighting, this is a problem.
Temperature is the major factor in figuring out when to plant. I sprout my seeds at 85-90Â°, which speeds them up greatly. The fastest I have ever had them sprout is 3 days, but at room temp they can take weeks, and some simply won't sprout at cool temps. Then, once they are established, and growing in the pots, the temperature will greatly affect how fast they grow. I put my early chinense peppers on the heat maf early on, until they get a few sets of leaves, though eventually, I grow them at room temp. You'll have to figure out how all of these will affect your growing of the peppers, before you can say when the best time to plant them will be.