I don't start mine until early March, that gives them 2 months' time before going outdoors. I remember when the date for our last frost was May 31st, now I can put plants out May 1st and usually not worry about them. If I get a cold night, I can move them into the garage if need be. And I definitely don't want to be repotting them all into a bit larger pot, at 2 months they need it or be moved. I just don't have the room to do that.
The majority of the space is taken up by Impatiens for the front porch, I need at least 60 of them. It's deep shade (covered porch plus a 50+ year old Magnolia Tree 10' west of the porch), regular impatiens are the only thing that not only grows but stays looking very nice through fall's first frost. Anything else I've tried there fizzles out and stops flowering, the vivid colors on coleus fade to all just pale green, Sunpatiens and New Guinea will flower, but not many flowers at all.
I do have to do my planning and figure out how many of each yet and soonish, what I'm going to have in each container. That helps a lot when it comes time to buying them... if I don't have a list, I always end up over-buying by a lot. When just trying to go off the top of my head what I need for where, it always ends up costing me a lot more!
Edit just to add that anything I start from seeds are those things I can't find locally. I can find regular impatiens for instance, but not in the variety you see online... just the basic plain single tone flowers.
