I'm a US citizen being sponsored by my spouse.
Here's my timeline:
Application received – 09/10/2018
AOR received – 12/17/2018
Medical Exam Request – 01/04/2019
Spouse received approved letter of eligibility as sponsor – 01/04/2019
Medical exam appointment – 01/15/2019. I was told it will take up to 10 days to process the results and submit it to IRCC, assuming there are no abnormalities. I made and completed the appointment while in Vancouver, BC since I'm currently here visiting.
At this point, I'm still unable to link my account online. Good luck, everyone!