I started quite a few seedlings early, but am culling them through a strategy called "neglect."
The other strategy I am using is "limited shelf space" in which I have to select about 30% of the survivors to pot up without taking up additional space. With many good survivors competing in this second round, I made uneducated guesses about which ones I might want to grow. I enjoy making these decisions, although I also enjoy never knowing or regretting what I am throwing in the bin. Leaf shape, stem color and stem thickness were my main criteria. One survived to grow another day based purely on having very narrow arrowhead shaped leaves. Another because the stem was very very dark. I'd be interested to know what traits you have seen in seedlings which correlated with other traits in foliage and blooms.
Next year maybe my husband will give up on his idea of a garage gym and I will occupy the whole space for seedling shelves.