Hey bro, for your estrogen protection, you'd be much much better off using an AI, like adex. Nolvadex does not reduce the estrogen in your body. It only limits the receptors that the estrogen can attach to. An AI will keep your estrogen levels in the normal range. Then if you still had a gyno issue, you can always take some nolva while you adjust your ai dose.
To answer your question, no, if you are on HRT, when you come off, all you need to do is go back to your HRT plan about 2 wks after your last shot since your goal is not to recover natural production. You may need to run the adex a little longer and slowly reduce as you transition back into HRT. It wouldn't hurt to see where your estogen levels are on HRT and if needed, include the AI during HRT as well. Good question, bro