You should water them thoroughly, when you water, wetting all the soil, especially around the edges. Then, wait a couple days, or however long it takes for the top layer of soil to get dry. Alot of guys say to wait til the top 2" is dry, but I think that's too much, in a small pot like that. Yeah, it's a good idea once you get to a pot 2 gallons or larger, but not in such a small pot. I'd wait til the first 1/2" gets dry, to water again, then repeat.