I've got two pregnant mares. One of them we didn't know was pregnant when we bought her (anybody who tells you it can't happen from just one mating doesn't know beans) so we don't know when she's due. She's also a maiden mare....or was, so this is her first foal. I hate first timers. My question? Oh yeah, I've forgotten how long from the time they first start to bag up until they should more or less, kinda sorta be due to foal. She's just starting to bag. The other mare is due May 15th and hasn't begun to think about getting milk yet.