Hi rookiethegooner
Please ask your local rescue for advice, if you are unsure, but I think it is far too early to start taking hoglets in for over wintering. There were small hoglets here until the end of November last year. They put on weight very quickly and I imagine the little one there should have plenty of time to put on the necessary extra 100g needed, especially as, presumably, you are supplementary feeding and it is eating well.
It is far better for a hoglet to grow up wild, and much nicer for it, rather than being cooped up in what, to it, must seem somewhere alien.
Please see
http://www.britishhedgehogs.org.uk/pdf/Hibernation-Weight.pdf
