you cant know for sure until the retrieval. If the estrogen levals are increasing that is good. There will always be some larger and some smaller follicles, and the clinic will decide to trigger based on the size of the larger follicles, but also whether there are a lot of smaller ones developing. For example I had a donor and she was a "slow starter" with a few large follicles, but then she caught up and after 10 days they triggered her and there were a ton of smaller follicles that caught up in the last few days. That may not be too helpful but just to say the important thing is that the Estrogen keeps rising and that there are follicles developing. Good Luck. You deserve it!