Assuming you are over 21 and have all of your training and diet in check (i am too lazy to check) i would start with 20 mg a day to start with an go from there. from what i have read using a SERM like nolva does not hinder gains, it just prevents estrogenic effects (like water retention) which could make you appear less full and minimize strength a tad.
here is a quick exceprt:
Nolvadex does not block any of the gear receptor sites, so it does not make any gear less effective. A lot of people believe it does simply because when they use a high androgenic compound (ie. testosterone), they lose a few pounds of weight and some strength (a bloated muscle/joint is stronger). This is simply because Nolvadex blocks the estrogen receptor sites, so you don't hold as much water (estrogen causes water retention). However, the gear that you are taking is still working the same at building muscle.
obviously you arent using test and probably wont even need nolva with this low dose but it never hurts to have some on hand.