Hi, I
would not put tons of blankets in your whelping area. The puppies can get rolled up in them and lost ! I use just 1 thick bath towel only. You can use a heat pad with cover
on low under the towel. I would start feeding her puppy food too and all she wants to eat. Mine sometimes have a dark weird poop right before they whelp. I use a 28 qrt plastic storage box for walmart for my box. It's just tall enough so the pups can't get out until they are older. Put the heat pad in only 1/2 the box so mom or pups can moce off it if they want to. To hot is not good . 90% of the time ( for mine) the temps go up and down for about 1 wk and then down to 97- 98. Most of mine get thier milk in the day of, or 2 days before. Make sure you get a after hrs phone number for a vet that can help you in case of trouble. Mine seem to like to have their pups in the middle of the night when vets are not open.
Good luck.