here's what we know and dont know
1) nandrolones are progestins. they can cause an increase in prolactin, and a potentiation of estrogen.
2) nolva upregulates progesterone receptors so it shouldnt be used on a nandrolone cycle
3) depending on the ester, most of the active nandrolone should be out of your system by 2-3 weeks.
4) there are no studies, but it seems logical that there shouldnt be any conflict at that point once the majority of the active nandrolone is out of your system
5) I made a thread here a while back on this same topic asking for peoples experience, and a few indicated it was not a problem for them, even one member, if I recall, who was gyno-prone.