Posting this to help with anyone else who is trying to figure out how to make sense of the "disappearing permit" and "Step 3 FSMB" tricks.
I took my exam on Thursday Sept 6th, and my scheduling permit disappeared yesterday (Monday week 3) sometime mid-day to evening. This is noteworthy because a previous poster took their exam the day before me on Wed Sept 5th and had the permit disappear a day earlier than me. At the time that my permit link disappeared, I still could not sign up for Step 3. However, just this morning (Tues) I was able to sign up for Step 3.
This makes sense: the ECFMG sends the score to the FSMB, so you'd expect a delay between when the ECFMG registers my score and when the FSMB registers my score (putting my step 2 critical thinking to good use here!).
(To those just joining the thread now, the step 3 FSMB trick is described in much greater detail in earlier posts, but essentially it is believed that if you passed a given step exam AND have already taken all the other step exams prior to step 3, you will be able to sign up for the step 3 exam a day or two before the final score comes out)
Conclusions
1) The day your permit link disappears is not conserved across all people who will receive their score on a given Wednesday, and possibly correlates to the day you sat the exam originally (perhaps Wed, Thurs, Fri exams correlate with Sun, Mon, Tues link disappearing, for example).
2) You may be able to do the "FSMB step 3 trick" a day after your permit disappears.
I really hope I passed, as with the rest of you I was freaking out over this exam... good luck everyone.