Miracle Grow is not recommended for growing cannabis at all.
However, there is one exception - Miracle Grow Patio.
Miracle Growa Patio is the ony one you should consider using - it is a complete secondary feed.
If you wish to buy a soil medium that is specifically manufacturered to grow ganja in, then check out Plagron Bat Special Mix. it contains five different types of peat, sphagnum moss, perlite, and bat guano. Should not have to feed the plants for at least the vegging period - if not for the entire grow.
If you are using decent soil then there is no way you should be using nutes so soon. you will only over feed the plants and create problems for yourself. It is worth bearing in mind the that cannabis burns very easily - so you should always start with a quarter strength solution to begin with, and build up.
good luck