I did this one year, Mum, and kept a couple of plants going through the winter on a cill in a warm sunny room!
They were very spindly by the time they were due to go in the GH in the Spring, and because of the risk of them getting cold, it was a big gamble, so I rather gave up on the idea, as the others caught up very easily!
You could take the side-shoots, and use those as new plants, but there again, you might only get a week or so ahead for all that effort!
(And I'm giving up on Sungold next year, the skins have been like leather and most of them split)!