MrsP, Sorry to hear you go the BFN you expected. I've done back-to-back stim cycles this year. I did IVF#2 in March. AF started 3 April (day after BFN) and I started synarel again at 7dpo that cycle (6 May - long cycle due to delayed O). I just had to go in at 7dpo for a progesterone test to confirm I had O'd.