The office manager at my medical office calls in our hours for example if the pay period lands on a Friday, she will call in the hours and just guess what our hours will be on Friday, by what we usually work. Well if we get more or less? Then what? She doesn't put us in for a lunch hour either. Is that legal to call in hours before they are worked?

Yes, then on the next check if you worked different hours the next check would be adjusted to pay or take pay for differences.