fda BTD procedure
One detail that I have mentioned before is that the FDA offers a free meeting to discuss whether the data is ready for a BTD application. I suspect that they do this to stop every company doing BTD's on every drug. A quick meeting whereby a reviewer tells you that it will likely fly or not fly is more practical. The reviewer would also likely tell you that the data looks good but that they suggest wait for x number of patients at x rate of CR.
Way back when BTD was mentioned for the first time the company was coasting on 66% CR rate on a one and done. Of course the FDA is going to say BTD is likely with that kind of data. Now the real world has happened (optimized and non-optimized situation) so they would need an update on what is needed for FDA BTD.
My overall point is that the company doesn't have to submit and then cross fingers. They can run it past the pre-reviewer and then submit with higher degree of confidence based on what the pre-reviewer suggests. When the y do submit it will be for that reason rather than any previouslyl published timeline.