Just in case you're going down the traditional mailing to FBI way...
1) Timeline-wise, 8 weeks for my case... 1/17 fingerprint delivered, 2/17 fee posted to credit card, 3/13 received FBI result (address in Canada).
2) If you choose to pay FBI fee by credit card, you can wait till they post the fee to your credit card, then arrange the medical.
3) I picked up fingerprint card & cover letter from FBI office, and the cover letter looks like this (I typed here based on a hard copy. You will need to reformat it if you're going to copy it to use):
COVER LETTER
Date:
Requestor Name: __________________________
Requestor Address: __________________________
__________________________
__________________________
Attention Record Request:
I, ___________________, am requesting a criminal history background check for personal review pursuant to 28CFRS16.30-16.34. Please mail the results of the check to the folowing address:
__________________________
__________________________
__________________________
__________________________
I have a reason/date that requires expeditious handling (optional):
(PLEASE PLACE DATE/REASON ON OUTSIDE OF MAILING ENVELOPE)
Date Required: _______________ Reason: _______________
If you have any further questions, please contact me at:
Telephone: _______________ Email: _______________
Sincerely,
_______________
(Signature)
4) After you've done the medical, the DMP will immediately give you a green form IMM1017 (Medical Report - Section A, copy 2, for person examined). That is what you need to mail in together with the application package. It has a unique number with bar code on it and that's what the visa office will use to match up your file with the medical results that the DMP send in.
All the best!