wait for RFE
We had to go through the same situation. If you have registered for online notifications then you will get an email about the RFE. The actual letter reaches the lawyer around 7 days after the RFE was generated. So you have enough time to complete the medical tests once you get the RFE email and then submit the response immediately when you get the letter.
The only thing is that USCIS sends back the original medical form along with the letter and asks the doctor to update that form.
Hope this helps.
EB2 Priority date July 2001
member CA chapter