Are you asking how much time off you should have or how much time off your wife should have?
I guess either way I'd say I don't think it matters. You could start trying to conceive the day after you end your cycle for the simple fact that you probably won't conceive right away and, even if you did, the evidence does not support the notion that DNP is teratogenic (i.e. it does not cause birth defects).
As for you (the male), there was actually
a study published at the end of last year. It stated, "The present review paper summarizes the data available in the literature concerning dinitrophenolic compounds and evaluates male reproductive toxicity in experimental animals... 2,4-dinitrophenol (DNP; CAS No. 51-28-5) did not show testicular toxicity in laboratory animals according to available literature."
Now that's not to say that DNP is decidedly and absolutely safe. The evidence just doesn't support the idea that there's any overt danger. If you want to play it especially safe, you can wait a couple of weeks. If it were me, I wouldn't be worrying about anything, but that's just me.