12 weeks before you plan to TTC is how long to be on diet.

I am not following your question - are you worried about losing too much weight too fast? While keeping fat and protein the same then just add calories to keep weight on (once you've lost to BMI 21, that is)

Which plan did you get OR which supplements are you asking about? Not all supplements work the same so if I know either what plan you got or what supplements you're asking me I can tell you.

We haven't used the tonic water much. It is fine if you want to add it in, I'd probably just give it to hubby though, 1x a day, in addition to the soy milk if he'll drink that.