Unfortunately that soil is not a great choice, don't get me wrong, it will work, but it already has time release nutes in it, so for 3 months it's a balancing act if you add additional nutes, because you don't know what is released (NPK) when, and at what rate. As far as watering, don't water every day. When you do water, thoroughly water around the outside edge of the pot, and work your way in towards the center with a lesser amount, you want to force the roots to search for water and expand towards the edges of the pot. Once thoroughly watered, allow the soil to become pretty dry, almost to the point of the plant drooping a bit. When the pot is dry, pick it up and note the weight, then water and again pick up the pot and note the weight (in your mind, although some actually weight their pots). This will give you a decent idea of when the plants need water. Also, don't get a moisture meter unless you go real high end, like BlueLab. The cheap two prong Moisture/PH meters on Amazon are notoriously innacurate. Hope this helps.
