She doesn't look quite ready from the pictures, as was said above. But you carefully watching her is critical at this point. What she is doing is repositioning the foal, I would guess, and if baby is laying on a nerve, it can be painful. We have watched oen of the mares on here, lay down and push, and we all thought she would foal that evening. After 3-4 hours of watching, she stood up and started munching her hay. She didn't foal for a week, but it was a healthy baby she brought to the ground, safely. she was just moving the little one around.
Since we can't actually "see" her to watch, you could discuss what you are seeing with your vet. Just a phone call might be enough. If we could "see" her, perhaps we could be more help. But, I would advise you to read through the pinned threads at the top of the forum, so you are prepared and can be of help to her should she need you.
This is a stressful time for you and the little momma. But, she doesn't look quite ready -- baby still laying wide, no "slab-sided" look, and baby isn't quite forward of center. She hasn't elongated as much as I think she will, and there doesn't seem to be the puffiness of pressure on her vulva yet. I'm not worried about her udder, as she could foal with no udder at all, and once she's foaled she could have a full udder in record time. So don't worry about lack of milk -- it will come.
But keep your eyes on her. You will see her rolling, pushing her butt against the wall or a post, and those types of movements. Her manure should change to look like cow patties -- very soft and squishy -- as she cleans out her system in preparation. But again, give your vet a call in the morning if you need some extra security. I believe she is just getting this baby in position, but we want you to be prepared and calm and ready to help her. So, give a call in the morning, but be very factual with your vet -- just the facts, so your vet has a clear picture of what you're seeing. Don't "guess" just tell her exactly what you are seeing. S/he may want to stop out and check on her for you, but from the pictures I think you're just seeing some repositioning behavior as she "shoves" this little one around.
Keep us posted. We are here for you!!