Most everything is started on a couple of different days. I like to space the starts out about 10 days. I think of this as "hedging my bets, Bugkiller .
The tomatoes may have 3 different starting dates and the early plants will all be up-potted into larger containers.
Of these 4, only squash, etc. will not be started in "community" containers and moved into individual pots or cells.
I start mine on the 1st of Dec (getting close) then every 10 days I start some more.
All I start indoors are tomatos, peppers and egg plant but this year I will cut back to about 75 of each.
Yep, tomatoes, peppers, and eggplants can be started as early as you want, BUT, they will need uppotting as they get bigger, more space, and more light. Also, care to ensure no bugs or disease.
Things such as melons though really should not be started more than 4 weeks before planting out. They can be, but things become more difficult. If they get too long it can take 2 persons to plant them out, one to hold the vine which is very fragile, and another to do the roots which are also very fragile.