Maintaining your crop
Make sure that you keep your tomatoes well watered every day, just so that the compost remains moist. The seeds should begin to show any time after a week depending on how warm it is.
Once the seeds get to about 6cm, they will need to repot in individual pots. You can use the same sized pots you grew the seeds in (7.5 - 8cm). Ensure that you look after the roots as you pull each plant out of the pot, and then make a hole in the compost of your new pot and drop the plant in. Ideally the plants will then need more room, so repot as necessary as they grow over the months.