I think it was Buzz who posted the video here, not me.
I think all the muscles dissected will swell and compress the IJV again mimicking new compression. I would say wait 90 days before you can judge. Some folks get the peak of the inflammation later. If you really wanted know how long this can take, take a look at the @M_UK posting 9 months after Styloid & C1 resection. He did an awesome comparison where he even quantified it in fluid dynamic software. I also posted a link of a study that looked into jugular vein collapse after neck dissection which shows you need 3 months to fully heal from swelling compression of the IJV. You can see both links below