half marathon strategy using races to gain fitness

I have 3 half marathon races 3 weeks apart each. How would you go about this when 3rd is your A race at 6:25 pace?

Plan A:

Race 1) run first 1/3 the race at 6:25, finish the rest for 6:45 average

Race 2) run first 2/3 the race at 6:25, finish for 6:35 average

3) 6:25 steady

Plan B:

1) 6:45 steady

2) 6:35 steady

3) 6:25 steady

I plan these methods as I stink at negative splits . PR from 2 years ago is 1:24:10, but during a marathon (NYC)