Yes technically there is a rule, you went for an upfront medical, thats something that you did before submitting the online application (that's one of the processes). For someone like me who has already submitted application without a medical, IRCC is supposed to send you a letter for the same.
Below is the information on the official webpage:
"Getting an exam before you submit your application
You have the option of getting an exam before you apply. This is called an upfront medical exam. To get one, contact a
panel physician directly.
You can get one if you apply to:
- visit (including parent and grandparent super visa)
- work
- study
Getting an exam after you submit your application
We’ll send you instructions on how to get your medical exam done. You must go for your medical exam
within 30 days of receiving these instructions.
If you don’t follow these instructions, we may refuse your application."
The above in red clearly says to follow instructions, that is why I am confirming from you out of worry.