The standard recommendation is to transplant seedlings when they have two sets of true leaves. With most of my seedlings this year, I have been doing it when they have one fully developed set of true leaves.

There are many people who do not divide, they just snip off the extras, leaving the healthiest seedling to grow. If you have enough, that is certainly the least stressful way to go about it.(both for you and for the plants)

With many of the seeds I bought this year I only got 10-12 in a pack, so I really didn't want to sacrifice any of them to the scissors. I decided that as long as I was very gentle with them, it would be easier to divide and transplant before the roots became tightly intertwined, hence my decision to divide when the first true leaves formed.

Only pick them up by the cotyledon leaves, the stems, roots, and true leaves all bruise easily.

You don't say what you growing, but with one seedling per six inch pots, it is very easy to end up with a pot that remains too wet. I would only water when I am sure they need water and then only from the bottom, and let the water wick up, stopping before the top of the soil looks wet. Al

Thank you guys I know what I need to do now.

Abe