It's almost always hard to tell by the bag when they are going to foal. My mare last year was bagged up about 3-4 weeks before she foaled. And she waxed for 2 days, stopped for a day and the waxed again before foaling. The only sure thing that I could look for and "know" that she was going to foal was by looking at her vulva. It not only was long and relaxed, but her's had actually started to unzip to where I could see some of the pink. So that is what I would look for. I'll post some pics that we took about 4 hours before my mare foaled so that you can see what she looked like.
