Usually the day of, they will not eat and will clean their system (Poop & Pee). Temp will drop to around 97-98 and may go back up a bit. She may get kind of shaky not long before also. What a surprise for you. You are doing a wonderful thing by her.
Every dog handles milk diffrently. My bitch drank about half a gallon of milk, about 8oz of honey, and a dozen eggs over the day of labor, during labor, and the next day because that was all she would accept and she was meserable after 12 puppies and 24 hours of labor.
But you need to know your dog. Most bitches have dirreah after the puppies. Personally i let my girl chow down all 12 placenta. Sure, she had tar stool for a few days but she ate about five pounds of pure super rich protien and she needed it.
Continue to take the temp. Sometimes there are false drops. If it stays down, within 24 hours. And be ready.
Let her do the work, she should trust you, but be ready to rip open bags, clean out noses and mouths, and rub puppies and cut umbilicals. Moms are rough but if she seems excessivly so, intervean and snip the cord for her.
Pups wont instantly nurse, don't worry if they don't for the first hour or so. Start massaging her nipples if you have not already to get them simulated and producing.
watch mom carefully when she is opening the sac. Be ready to grab the pup to break the sac. My mom used her paw to hold the sac & broke 2 of her pups legs. The dental floss came in handy when one of the umbilical cords was still bleeding. Tie it off 1/2 inch from the body & trim the floss short so mom won't pull it. Also give mom lots of praise she is probably scared & tired.