I have completed my usmle application and now I am waiting for the schedule permit. I will share my experiences for you.
I applied for Ecfmg 2019 and went through Notarycam process. You also have to do it and wait about 10 working days for the process to be completed and they will notify when the process complete and you can begin apply for usmle. All you have to do in this step is upload your form 186 and passport to Notarycam as the link inside form 186.
After about 8 days in my case, you will get your permit to apply for USMLE. Then you have to pay 910$ and you will get your form 183, you download the form, get the medical school signed and mail directly to Ecfmg. Remember that after 14 days from the day they receive the form, if you do not get any mail from them, do not hesitate to give them a call. In my case, they thought I do not sent them the letter to confirm I am graduate so they did not process my application until I called them yesterday.
Wish all of you good luck in your test.