Chromo, you are so right on! Damned you're a breath of fresh air! I start my seeds in 9 cell pk. (Individual pk from 72 cell inserts for plant trays). First transplant into 8oz styro coffee cups (they 'breathe.... plants love them!). This promotes great seedling growth! From there, they go into red party cups.... you get it. Pot up in very small increments as needed, regardless of what growth stage they're in, & don't disturb the root/soil ball, trying to keep it whole so no feeder/root hair damage. Ofcourse using 1/2 strength big bloom as a transplant tonic ea time, & going up in richness in soil ea time.
-- I used to compost & make all my own orgainc mixes, but age, arthritis & nerve damage kinda limits throwing compost around with a shovel/pitch fork, & then I found FOX FARMS (& of course my old favorite, pro-mix organics, equalivent to happy frog), & I'm more than happy with the change. Costs a lot more, but well worth the expense!
-- Your love of plants (& stones ),& your occupation/education, has made you into a great grower even before you grew! So what took you so long? You should have been doing this ages ago!