OK,
I recommend the following fertigation strategy. I also recommend that you measure EC or PPM to be able to follow my directions so work on getting a meter.
1. Fertigate daily: The pots are too big to do more than that yet, but they should be able to handle 1x per day without over-watering issues. It is important to fertigate daily to maintain high levels of Ca in the nutrient solution.
2. Fertigate always: all water that you add should have the proper blend of nutrients (including Cal Mag!).
3. Give a strong dose of Cal Mag, (at least full strength).
4. Don't burn your plants with high EC. You can probably get away with 1.6 (1600) as inflow with 1x daily fertigation at this stage. You are going to run a little hot to keep cal mag high, but you need to be careful to not burn them. You should track both inflow and run-off EC and I would try to keep them 1600 in and 1800 out. I explain how to manage run-off EC in my guide. If you cannot yet measure EC, you can still proceed, but it will be helpful to be able to set those values and track them. In either case, you should watch for tip burn. Tip burn is a sign of high EC - it is not related to other nutrient issues that may occur during this process. So if you see tip burn you should lower EC (concentration of nutrients) but don't lower Cal Mag!
I hope this helps!