Your soil has ferts incorporated into it. Saying that, if you over water, you are also over feeding, which causes lower leaf burn. Also make sure your ph is on the low side, my suggestion is somewhere around 5.5.
So, as suggested above, let the soil dry out for a few days, check it with a moisture meter. Then flush the soil with low ph water and let dry out for a day or so, then water only when the soil is dry an inch down.
Also, when you water, keep the fluid away from the stem, water in a circular direction toward the pot's edge, making the roots reach for the water.
Good luck and keep us abreast of how it is going.