It’s great that you’re feeding the little hog, but if it’s really tiny and it tries to hibernate it might not make it. So the best thing to do is weigh the little one. The minimum recommended weight to survive hibernation is 450g, although it might get away with being a little bit less if it’s attending regularly for food and you are in a milder part of the country.
I would contact your nearest carer – you should be able to get a list of the nearest ones from the BHPS – and take their advice. They will be familiar with your local weather conditions. If the hog is really small, they may be able to take it in for over-wintering. If they do, make sure that you can have it back afterwards to release it where it came from.
Before you weigh the little hog, I would have a box/pet carrier ready in case it is very light. I usually put sheets of newspaper on the floor, because they almost inevitably spill some of the food and water you will need to provide. You can either use torn up strips of paper for the hog to burrow into, or some people use small towels. Be aware that hogs are excellent at escaping from boxes.
You will need some thick gloves (gardening gloves are ok) because their spines are very sharp when they roll up. I usually weigh them in those 1 litre ice cream containers. An underweight hog easily fits in one. If you try to put them directly on the scales and you get a wriggly hoglet, it might be a bit difficult!
If the hog is over 450g you can release immediately, where you got it from. They soon forget about being weighed. If under 450g. take the advice of your local carer, as above. Keep feeding and providing water for the hogs as long as they are still around.
Good luck. Let us know how you get on.