How to take cuttings of surfinias

When can I take cuttings of surfinias and how best to achieve results

Around now i would of thought before they begin to die off.
Theyll survive just keep on dry side and they will require warm and definitely frost free conditions over winter.
We get 1000s of them as cuttings in February in the nursery where i work, (grown by plug supplier over december/january in a warm greenhouse).
We have to keep them above 10 degree Celsius at all times throughout winter.
Kept on dry side or else they will rot, esp sitting there over winter growing very slowly.
Probably easier just to buy plugs next spring