With coco, I recommend a complete hydroponic formula. Before mixing my own, I used GH Flora 3-part. A friend who grows in ProMix Advanced (coir-based) is getting solid results with DynaGro plus Cal-mag. A TDS meter is very much your friend when growing soilless or hydro. I use mine to monitor effluent. When effluent TDS match what you put in ... you've found the plants' sweet spot at that point in their growth cycle.
MaxiBloom is not a complete hydro nutrient; it's meant as a soil supplement. Imo your urgent purchases right now are a TDS meter and a veg nutrient for hydroponic or soilless apps. Some firms make coco-specific nute packages.
The thing I have not yet mentioned is water quality. I use my TDS meter to check my water quality. it changes seasonally. Right now it's a very nice 50ppm indicated.
If your water is very hard ... or worse, contains sodium (say from a brackish municipal supply, a Southwestern well or (gasp!!) a water softener), you need to filter it, or find a better water source. cn