That's great clear advice, Tee Gee. I have to add though that for me it would be a great luxury and rather expensive in compost to plant on each seedling into a 3" pot.
I've pricked mine out with one, two or three to a 24 module tray. So some will be singly planted and some two or three in a clump, ie. multisown. As long as they're planted out before they exhaust the compost, it seems to work fine.