I don't like to rain on anybody's parade, but judging by when you started this thread we started at the same time. My ladies are over 2' tall and in Flower since 5/26 and your still showing babies. I hope I'm wrong, but if this is as far as you have gotten then you should try the old tried and true method called "KISS" keep it simple! You're doing too much and wasting money at the same time. I went in with the same thought process of using water only soil and seeds only. I picked up Detroit Nutrient water only mix, you can pick it up on Amazon for an arm and a leg! One bag will fill 3=5 gallon containers or 4-3 gallon containers. Since I changed my mind from 3 gallon to 5 gallon I didn't have enough, so I picked up FFoF. 3 to 4 days after transplanting the Detroit Nutrient pots (2) showed browning and yellowing of my leaves while the FFoF pots (2) did just fine. Nobody can tell you how much water your plants need exactly although telling you not to water till overflow is best practice. Why wash out any Nutes or supplements that you add and you will need to add. Just watch your plants daily and you will start to recognize when they show signs of needing water. When you over water your plants will slow down, under water and they wilt, just enough and they spring into action! Watering needs will change as the plants get bigger. By the way 1 plant per pot! Anything more and two things are going to happen 1. the roots get intertwined and separating them without damaging gets harder. 2. the two plants together are going to fight for nutes in the soil. Also you have a 2x2, an experienced grower can make more than 2 plants work, but you said you were a noob, KISS. You have how many plants growing just to flower 2? most seed banks I check get about $10 per seed, KISS save some money germ 3 or 4 seeds in rockwool or a 8 ounce cup, pick the two that show the most robust growth and add to the tent in 3 gallon containers and hope that size limits the growth to under 30 inches. You'll learn a lot about training with 2 plants in a 2x2x48 so again KISS. How much room do you have in the tent after you subtract the room taken up by the light and the height of the container that holds the plant? When you plant hits12" you hace to switch to flower and even then it could double or even triple in height that could be 24 to 36" with a photo. Your pushing it. I use a 3x3x72 with 4 ladies and I promise you space is becoming a major issue day by day. I went from transplant to flower/bloom without any added nutes or supplements. I started using soil amendments on the same day I started my 12/12 cycle (Meigs formula 1 & 2 along with Mighty Bloom) that's it. As a noob I didn't look for perfection in my 1rst grow I'm just looking for completion and to at least break even on a cost basis. We should keep in touch, I plan to get a 2x2x48 in about 2 maybe 3 weeks I'm just waiting to see the light at the end of my 1rst grow, actually I see it. I got some auto seeds that I think would be better suited for a small short tent as apposed to photo seeds. I'm curious about how your tent size will become an issue when you get into the flowering stage. A good idea may be a fast seed using SoG, many plants, grown short, acceptable yield, shorter time frame! I'm sure the experts will tell you better ways, but right now I'm a happy happy camper. Oh, don't worry so much about the soil you use, but rather how it's stored where you plan to buy it. Avoid anyplace that stores their soil outside (bugs), look at the cleanliness of the store and try to gage who long the product has been sitting there, if it has dust on the bags keep moving. Like I said the experts and well healed on this site can definitely give better info than me but just keep it simple and you have less a chance of anything going wrong.
Good Luck