My tomato seedling regime is quite labour-intensive. Our summer is generally shortish and not that hot, and I start everything pretty early.
Seeds broadcast in screened
compost in plasic icecream cotainers with drainage holes.
Mark the names!
When the seedlings get their first set of 'true leaves' ie, proper tomato leaves, rather than generic-looking 'leaves'.
I dig the plants out with a butter knife, separate them and bury them in individual pots of screened
compost right
up to the new leaves.
Tomatoes will grow new roots from any areas that touch the soil, and the more roots, the better.
I generally pot-up twice: at true-leaf stage, and when the plant gets larger and 'leggy' again.