Some hogs hibernate much later than others and some choose not to hibernate at all. The best thing to do is to keep offering supplementary food. The hogs will probably come to rely on that the colder it gets and the more difficult to find wild food. Water is best made available all day every day, even through the winter.
If you think the hogs are small and might need help, you might need to weigh them. The minimum recommended weight for hibernation is 450g.
Good luck. I hope all goes well.