I had a bit of an argument with my calmag and my lady (née ladies, tear), and still seem to be in the catch up end of helping, but at least it isn't getting worse. As near as I can tell, you just kinda guess where your levels/dosing need to be, watch and react?? Probably not the most stellar advice, but that's what I've garnered from my readings.
DON'T GET IT ON THE LEAVES!!
Welcome and happy growing!