My oncologist has suggested i do 2 years on Tamoxifen before swapping to Zoladex + AI (I refuse to have my ovaries removed). Apparently this replicates a research study done. However, I don’t think there is any particular benefit to staying on Tamoxifen for a particular length of time before swapping to an AI once you are post-menopausal because the AIs are more effective at suppressing the cancer cells. But you might want to ask your oncologist about managing osteoporosis risk with AIs and any other side effects that might be problematic for you. Good luck.