the leaves are showing signs of nute burn that MG soil has a lot of fert in it your best bet is Fox Farm original or Ocean. I wouldn't add anything at all until you have 5 blade sugar leaves when they stutter like that its usually the root developing or you're using the force too hard. Staring at a plant stunts growth j/k it seems like it tho. Keep on the water ever time the pot feels light (best watering method) NO NUTES she's burnin! give it a flush let it dry out water for a week then cal-mag. If you tend to over nute and you cant help it buy organics they are forgiving as opposed to chemicals that have a quick release. Plus I look at it this way if its organic who's to say that a situation where the exact amount of nutes you fed to it wouldn't happen in the plants natural environment. Also try to keep everything on regiment exact times for watering, lights, and everything they like stability. After the cal mag in two weeks give them bio root and oh yeah start topping right now as soon as they get that size I top get em bushy you want short stout little octopus's good growing to ya