You have a Haworthia, Echeveria, and Gasteria from left to right, I think. They make a compatible group for a sunny windowsill. I realize those 3 pots are perfectly matched
but I think they are going to be too small for your plants very soon. The middle plant looks most in need of space... it will be happier in a pot that's just bigger than the width of the rosette. That size would work for the other two plants in the near future as well.
If and when you do repot, use containers that have holes at the bottom and are wider than deep. You can use bagged cactus mix or regular potting soil with added perlite/pumice/grit to 25-50% of the total. Various things can be made to work, but it's important that the soil be fast draining and not overly rich/moisture retentive. Do not disturb the roots any more than necessary when you repot, and wait a week afterwards to water in order to avoid complications (rot).
The actual watering frequency depends on a lot of variables (temperature, light, humidity, air flow) that change with the seasons and the weather. But the basic principle is to water well and then wait until the soil is dry before watering again. There is no particular advantage to allowing the soil to stay bone dry for any extended period, but there is a significant risk of rot if you don't allow the soil to dry out enough in between watering. Using a pot that matches the size of the plant (as described above) will help with watering, as will strong light (indoors, that means they should "see" the sun for hours a day). Maybe water once a week this time of year, much less often during the winter.
Hopefully others will chime in with advice based on their own experience.