advice on ph strips and when to start diet to conceive a girl

Hi, my husband and I are going to start to try for a girl in December or January and I was wondering when we should start the diet? I have a 7 month old son so I want to wait until my cycles are regular again before trying (cycle just returned last month).  I have been doing a lot of research (maybe too much lol) and feel very overwhelmed and somewhat confused with all the information out there. I am going to start by testing my ph but wanted any advice on what the best test strips are. Any suggestions? Also, it seems like O+12 is the best timing for conceiving a girl (my 2 sons were conceiving with BD before, during, and after O ;) but I'm nervous about finding when exactly that is. Any suggestions on the most accurate ovulation predictor is?

Any advice is welcome:) Thank you!

Hi I didn't want to r&r I think they recommend at least 6 weeks on diet and supps, I use the cb smiley face ov test set, I got mine from amazon a box of 20 for £26 and 1 box has lasted my 3 cycles. I can't remember what ph strips I got but on f&q there a whole section on ph testers some work some don't the ladies on ttc girl board use digi ph readers I think. Gl

 Thanks so much! GL to you too:) Hopefully we will both being seeing pink very soon!