How often should I be watering my plant? And how much water?
Hello 
well I guess it all depends. How old is she? Indoor outdoor? What size and type of planter (fabric, in the ground ect.).
@Lenardt if you take your finger and push it into your soIL and the top 1.5 inches is dry then she needs water. Also once she dris out pick up the dry pot and you can also use weight to tell if pots light waterms ig not then dont
When a plant is a seedling and just born, they only need misting. When they begin to grow you will water lightly in circles extending out from the stem so to stimulate root growth out. After you only want to water them when they are thirsty. The knuckle under the soil is good, as well is getting accustomed to what your plants weight is when dry. Over watering will bring on a host of issues from bugs to root rot, so letting them get thirst is a good thing. their roots will start hunting for water, and that will be awesome for your plant too. If you watch them and their leaves just begin to turn down, feed them. I am just finishing up my first grow, and getting the watering right is important.
In your circumstance you need to water the plant to runoff. Then wait a few days until she is good and dry and water again to runoff
His plant is 3 months old and just beginning to flower.
It would be a good idea to do a grow journal and ask all of your questions in one place so we can keep track of whats going on