As noted, it is best to avoid using coco that has been supplemented with only a few of the many required nutrients. It will be very hard to get nutrient levels in balance, properly proportion, with each other.
Feeding bloom/flowering phase nutrients during the grow phase will likely work but is not best/optimal.
Perhaps consider using 2-part MegaCrop powdered base nutrients with coco/perlite from the start or as the nutrients in your medium are exhausted/consumed. Check into orderering the 'free' (pay for shipping) samples from Greenleaf Nutrients, with their free small size enough for several small grows. 2-part MegaCrop will handle the whole grow, and presuming you start with RO or other low salts/ppm/EC water, unlike most base nutes, you generally not need bother with feed water pH measuring and adjustment.
