Need photos.
If I were you I wouldn't get too deeply into the nutrient topic. Cannabis grows fine without complicated multi-bottle "lineups." Eventually you might want to get into that. But, right now all you need is MiracleGro "Tomato" (or any fertilizer product that says something on the label like 12-12-12 or 16-16-16. I.e., those three numbers balanced like that. Not 4-12-8. The best way to think of this as a ratio. The first two are ratio 1-1-1. The last one is 1-3-2.). I've used "Tomato" to grow a plant. 5/8tsp per gallon of water.
But, it also depends on your soil. If the plant is in soil that already has nutrients, it may be complicated to know if/when to feed more. (If you transplant, maybe you can get the same soil. Otherwise, you need to be careful buying typical potting mixes at retail stores. MiracleGro Organic potting mix is lower in nutrients. Some people grow in that. Black Gold Organic is even lower. I think more people use that. Either way, you should mix perlite into those. I would mix 50/50. But, it may depend on the soil the plant's already in. If it's dense/heavy soil, then I don't think it would be good to make the outer layer of soil too light or you'll have a problem keeping the outer layer wet while the inner layer stays too wet. (Cannabis doesn't like to stay wet. It likes complete wet/dry cycles.).