I agree with Haleivi. As soon as we can discern their sincerity, they should be accepted immediately.
Unfortunately, almost all of the dayanim who are currently involved in geirus are incapable of making this determination, and all of them should recuse themselves from the process since they have proven themselves terrible at it.
This is obvious from the outrageously high relapse rate of geirim being chozer l’suram.
It is equally clear that the procedures that are being done are extensive enough and that the only problem is the dayanim themselves who clearly are unable to determine even after all these procedures what should be obvious at that point–whether the candidate is sincere.
If I was working at something and had nearly as high an error rate as they do, I would quit my job since I would obviously not be good at it. They should stop; they are being irresponsible and reckless.