For anyone else looking at the internview process for Canada (Montreal). I got the notice that my case was at the embassy on December 15, 2022. I had already done my DS 160 on November 12 so I waited until December 29 for them to send me Packet 3, but it didn't arrive. So I then sent in all of the information that is required from Packet 3 (the passport scan, the Interview document list signed off and the copy of the DS 160 confirmation page) with a VERY polite email. It worked! A few days later on January 6, I got the Packet 4 email that says I am good to book an interview. When I get to the pay the fee page it won't let me go any further until some appointments come open. It says there are "No available appointments" and to check back in a few days. I remain hopeful every day that they will open some dates.
It is hard to wait when I am so close to that finish line...... but this whole process is about being patient.