I start most things in standard seed trays and use seed starting media - 75 % and 25 % perlite. I use the standard seed starting trays cause space is very limited. Fans help seedlings fer sure and I rarely have a problem with damping off unless I keep something too wet. My bad. At 2 - 4 " or 4 leaves, I move stuff to regular plastic pots - 2 - 4 " depending on the type of plant.
Note that for my plumeria, I will likely start them in 4 " pots and go from there.
I use no fertilizer until I pot up. Then I also use Quick Start, Upstart or similar and Osmacote.
Ken - well commercial to an extent.
That is why I start so many seeds - 2,000 winter 13/14. I have a business called Pony Express Plants and sell from April - October at a local farmer's market. Nearly 100 % of my activity at ATP is for my personal plants. My city is where the Pony Express started. Also, a main leg of the Oregon Trail. And where Jesse James was shot.
While I am a Master Gardener and a Master Naturalist, my real learning came from being born on a farm and 40 years playing with plants and trying out what ever tickles my fancy. I have very eclectic interests.