Like I said that is fine, but if you want the most out of your plant you want to switch before FLOWERING. You need to up the dose of p and K and you will have no idea if you are overfeeding or underfeeding due to the mix of fert strengths. You COULD try to rely on a TDS meter to monitor your PPM to certain levels if you use distilled water, and keep it between around 1000-1500 for flowering ( i think, don't quote me ) But do you see how big of a headache it is to maximize yields with MG? You can grow a plant in MG, you can probably get a decent yield, but you will never get what you could of gotten without it as opposed to with it. Food for thought bro, just looking out for you and your plants! Good luck. They can grow great and beautiful up to vegetative... but you will have a small yield guaranteed.