How tall is she? The little ones like around 30"s seem to look like they are going to explode! Take pics from the rear, if she is still lopsided you have a ways to go, these little ones don't slab side out they just get an even belly. Your best indicator is her bag, if it is full in the am and still full and tight in the pm she is close. There are alot of indicators of going into first stage labor and shaping up, but some mini mares don't follow the rules. Write all of your observences down. Bring her up to the foaling area around day 285 or so to get her acclimated to the area and the bacteria. Check her twice a day and start your foal watch around day 300, I've had mares foal around day 305 and yet some go to day 355, each mare is different. Ask as many questions, post as many pictures, as possable, we are all here for you and your little mare.