How exciting!

This is the how I do my mare and what is recommended to our clients.

Just prior to breeding make sure you have your springs vaccines (6 way, WN, or any other vaccines needed in your area) and deworming done. Since she is a madian mare you should need to do anything but just in case find out if the stallion requires anything (cultures, etc.). Once your mare is bred and confirmed pregnant at 14 days it is best to not do anything until she is 45 days pregnant. This would included vaccines, deworming, no riding, or anything stressful like long hauls etc. Once you are past this point My mares go back to their normal routine. They continue with their normal feed and deworming schedules. At month 3 (optional, I do if they are out showing alot or around a lot of other horses) month 5,7, and 9 give the Pneumabort K vaccine (pregnant Rhino) which helps prevent late term abortions. Then at month 8 you will need to increase her feed and start putting on a little more weight on her, this will get her ready for lactation, which will take a great toll on her body. Then at month 10 you will want to do your spring vaccines again and deworm her. This will allow her the 3-4 weeks it takes her body to make the antibodies that she will pass to the foal in the colostrum. If the mare required a caslick to be placed after she was confirmed pregnant this is the time it should be taken out also. Now you sit and wait you will have many sleepless nights waiting for that baby. I have had good sucess with foal predictor kits especailly with maiden mares. You can get these on line or normally from your vet. It lets you know if the mare is getting close to foaling and they are easy to preform.

At month 10 you should also make sure that your mare is where she will be during foaling and the bedding that you will be using is in her pen/stall. Also get her use to late night checks if you are able to do those (my horses are at home so it is easy). This is also a good time to put together your foaling kit.
Mine includes: Vet number (in case I have questions), towels, a tube of bute paste (for mom afterwards), a garbage bag or bucket with lid (for placenta), latex gloves, a small container to put umbilical dip in (3 parts nolvasan solution to 1 part water. Do not use iodine or betadine), fleet enema. You can have more or less depending but this is all I ever use.

Once your mare starts to foal it should only take 20 minutes, the foal should normally stand within and hour and nurse within 2 hours. The mare will pass her placenta anywhere from immediately to 6-8 hours post foaling anything after that the vet needs to see her. Just remember never pull on the placenta as you don't want to tear it and have a piece get left behind. At 18 hours post foaling I have my vet out to do a post foal check they look the mare over and the foal from head to toe and pull blood on the foal and run and IgG test. This tells us if the foal recieved all the colostrum that it needed to protect it from infection. You will also have to increase the mares feed again to help her with milk production. It is important to have your mare in good flesh prior to foaling because once that foal starts nursing it will suck the weight right off her and it is almost impossible to play catch up if she is not at a good weight to start.

Here is what a 1000 pound mare requires a day in calories:
0-250 days gestation = 16,000 calories
Last 90 days gestation (starting 8th month)= 18,100 calories
Lactation (post foaling) to weaning=26,800 calories

Make sure that you ask your vet what he/she recommends and if you should do anything special for your area. This includes vaccines, feeding, vitamins and mineral supplements.

Hope this helps and good luck.
Sorry so long