I bred my mare almost three years ago. She started to bag up (I think) about 2 full months before she foaled. She got a little "baby size" bag as I called it, and stopped until about 3 weeks before she foaled. She started producing secretion about 9 days before she foaled. She didn't produce real milk until about 3 days before. And she didn't wax up until just a couple hours before she foaled. These are all rough date estimates, I'm guessing conservatively. She foaled at about 348 days. She never once went off her feed. She also got upset and ran around the round pen about 15 mins before she went down (a herd of deer went through the yard, which she GREW UP with!) She went down, but never really rolled, just started pushing. She needed a little help with the shoulders, but not much. So yeah, she's not exactly what I'd call normal, but with maidens...not much is normal.
The strange thing was, earlier that night about 6 pm I was giving her grain and watching at her stomach for movement. Out of NO where, she went from being as big as a house to looking emaciated (not really, but you get the point.) Her whole stomach cramped up and sucked up. I could see the head of almost every floating rib and her flanks blew up! I really don't know how to explain it, just like she sucked in REALLY hard and it pushed everything out sideways at her flanks. She looked so distorted...it was kinda gross to be honest lol. I probably sound crazy, but has anyone ever seen a mare do anything like this about 12 or so hours before they foal?