How Often Should I Water w/ Nutes?

I typically water my plants every two days. I haven't used much nutes in the past due to the fear of causing more problems.
I know no one on here likes or recommends MG but that is what I have, MG All Purpose Plant Food 24-8-16.

What is a good N-P-K for veg. and for flowering?

the food you have right now is OK for veg...not so much for flowering...nobody can accurately tell you how much your plant needs for nutrients as we can't see what your soil already has in it!

Now with that being said a good rule of thumb for nutrients is a 4:2:1 ratio for veg, and 1:3:4 for flowering...the amount of nutrients in your water can easily be determined with a PPM/EC meter...you can get them on ebay for about $10-$15...I use mine all the time...I personally use around 400-500ppm during veg of my "veg" nutes, but I also amend my soil with bloodmeal for extra nitrogen so I use an all purpose 10-10-10 for veg as the bloodmeal gives the plant all the N it needs during veg.

Basically, during veg give it more N than P/K...in flower give it more P/K than N...nitrogen is needed for vegetative green growth...P/K is needed for flower and trich production...but also don't forget your micro/macro nutes!(I use Shultz 2-7-7+micronutrients liquid cactus food during flowering, so that gives it the micro/macro nutes I need)