Is it time to transplant these indeterminate San Marzano tomato plants?

Question

As you can see, I have two seedlings in each "container." I don't want their growth to be stunted because they are so close to each other. I know that normally, you would thin them out at this point. Instead of thinning, I would like to have 4 separate plants in their own individual container. I live in an apartment building with lots of direct sunlight, so I will keep these plants indoors. I have a few questions.

1. Is it time to transplant these seedlings into their own containers yet?
2. Is the pot in the picture the appropriate size?
3. How deep should I bury the main stems in the new pot? I don't think the pot is deep enough to bury the main stem all the way up to the cotyledons without it having to sit on the bottom of the pot.
4. Should I add fertilizer (Miracle-Gro 24-8-16) after transplanting? (I am using Miracle-Gro potting mix, which claims to already have fertilizer in it.)

Answer 1

1. Yes they are big enough for transplanting I would say.
2. For now the pot is of good size, if they will grow larger in time they might need a larger pot then.
3. You don't need to plant them so deep as the cotyledons, but it would be wise to put them a little bit deeper than now, maybe half way to the cotyledon.
4. I would use fresh potting soil that already contains fertilizer. After a few weeks (when that fertilizer becomes exhausted) you can start giving it some extra fertilizer.