At my lining check, I know my RE will just bump ET a week and have you come back in the following week to check it again. If it's not thick enough by then, I believe, in my office, you would be cancelled. I'm not really sure what happens at my office if the lining is too thick. I never asked, but I would assume they would cancel you.
This is how my office appointments for FET's go:
Baseline - check to make sure you are suppressed usually about 1 1/2 weeks after starting Lupron. At this check in you get a new calendar with start dates for Estrace.
2 weeks after that baseline, you go in for the lining check. Here they want to make sure the lining is thick enough for ET. Here you get instructions on when to start PIO and when the actual transfer will be. (My office gives you 2-3 different dates an ET can happen at the start of the cycle).
1 week after the lining check is the ET.
exactly 2 weeks after ET, (Yes, my office is crazy and makes you wait 2 WHOLE weeks AFTER ET, that's 14 days.) you have your beta.
So for me, so far I've been delayed a week due to the cyst. So I went in for my initial baseline on the 17th, found cyst, Now I go back in for baseline #2 tomorrow morning. My original ET of 2/6 was pushed back to 2/14. And the same thing would happen if the lining wasn't thick enough. So I have the potential to be pushed back by 2 weeks if my lining isn't thick enough around 2/7.
Um, I hope that all makes sense, and it may have been more infor than needed, sorry.