Do mother raccoons leave their babies at any time?

Yes, even while the kits are still infants and nursing, the mother will leave them for short times to forage for food. If she doesn't eat, she doesn't produce milk for the young ones. As the babies are weaned at 8-10 weeks of age, they will follow the mother on foraging expeditions to learn how to find food. They usually will stay with the mother through the first winter and then go out on their own in the spring.

Not really, the babies stay with mother until they are about 6 month old then start to go off on their own. At my last house we had a mother who would bring her new babies up on our deck at least twice a week in early spring to share the cat food we left for our outside cats. As the brood got older they started becoming very independent.