So, here's what I've learned so far about tomato grafting.
1) Make sure you start a lot of seedlings, both of the root stock and the scions. I only succeeded with half the attempts at grafting tomato seedlings. No surprise I didn't go to medical school. There's a lot of planning (and luck?) involved in timing the rootstock to match the stems of the scions, so it's a good idea to have a lot of candidates for a match of the stem sizes.
2) Start the root stock about 10 days after you sow the