Really, you should use an aromatase inhibitor like Arimidex or Proviron. These drugs work to block aromatization of androgens to estrodiol, which is the primary culprit with gyno. Nolvadex and even clomid to some extent, do not come into play until AFTER aromatization occurs (which is, in part, why Nolvadex usage can have a rebound effect).
Nolvadex would be better than using clomid to prevent gyno, but it just isn't the best way available and may backfire on you post cycle. If you absolutely refuse to procure something like Proviron or Arimidex/Liquidex, maybe you would be better off using nothing, but keeping the Nolva handy in case symptoms set in.
Clomid 3 weeks after your last shot.