I think "YOU'LL KNOW" when it becomes strangulated. I was advised about when it becomes an emergency; severe pain was the tip off. I had to have a repair about 4 months post by pass surgery. When when it first happened it was painful, but I didn't feel like it was an emergency. After that first day or so ( honestly can't remember exactly) moderate discomfort would be the most apt description. At times when I'd feel it protruding and experiencing intrusive discomfort, I'd just push it back in and I was good to go.
Good luck on your procedure and a speedy recovery.