Congratulations on your baby tomato plants.

Once they have sprouted, true leaves should appear within a few days.

For what it is worth, I don't cut off the extra plants. Instead, I break apart the peat pellet and transplant each plant into a styrofoam, plastic or paper cup with drainage holes punched in the bottom of the cup. There are very good reasons for doing this, and the main one is that if you want a certain number of plants, you have to expect to lose some along the way before they get transplanted into the garden. So, it is best to have "extras" as back-up in case disaster strikes. The less experienced you are at raising from seed, the better it is to have extra plants.

Peat pellets work OK, but I only use them as "germinators" when I use them. I plant multiple seeds per pellet and, as soon as the plants reach a certain size, I break apart the pellets and repot into cups of good-quality sterile, soil-less mix.

I use the peat pellets to start some veggies, herbs and flowers but I don't grow anything to transplant size in the peat pellets because plants in peat pellets often have a lot of problems--including damping off and drying out too quickly.

If you keep your peat pellets too moist, you'll likely have damping off and plant death. I let the peat pellets get good and dry before I water the flat. I water by pouring water into the bottom of the flat and letting the pellets soak it up. The advantage to peat pellets is that they are quick and easy. The disadvantage is that they tend to hold either too much moisture or not enough moisture and it is hard to keep them "just right".

Today I am potting up my first round of tomatoes from their starter peat pellets to their cups--111 plants, 26 varieties. Usually I would have potted up the first round 7-10 days ago, but I haven't had time.

All these plants won't make it into the ground because half of them are "back-ups" in case the plants are eaten by: the dogs, the cats, the deer, the rabbits, the sow bugs and pill bugs or the moles, voles and gophers. If the critters or bugs don't eat the plants, there's still the chance of very late frosts (had one here in southern OK last year during the first week of May), hail, tornadoes, floods, etc., so I keep my back-up plants around a while....just in case. After the late freeze, I had to replant quite a few plants to replace those damaged by frost, and it was a pain in the neck to do it--but it was better than going without those varieties.

In the years when disaster doesn't strike, I have tons of extra plants to give to family, friends, neighbors, etc. or to take to plant swaps.

Dawn

I use a measuring Tablespoon to water my cups. It's one way to ensure that all the cups are similarly moist. It's also a way to keep from overwatering.