Watch her very close though. She could be a month away or a couple days. Watch her bag and her backside.
Do a search of the forum on foaling and read some of them.
Her bag will continue to enlarge and the nipples will point straight down. The nipples will actually fill themselves and look like little marshmallows very close to foaling.
If you can express fluid from her bag this is a great clue to nearness of foaling. It will go from clear to sticky to amber and very sticky and then turn opaque like 1% milk. When it does this she will most likely foal that night.
Also her vulva will get swollen adn elongated and may get very red inside.
All of these are signs that birth is imminent but she also could foal without any of these signs. The best thing is to watch her like a hawk and look for any changes in appetite, behavior, pacing, rolling, nervousness, any change can give you a clue.
Remember the mares dont read the books so all you can go by is what the usual things are.
Good Luck and keep us posted.