It depends on how much root growth has been made by the new shoot. I would wait until April at least before doing anything.

Totally agree with OwdB

Thank you, both, for the advice. I will wait for spring, then.

If you only layered it in autumn, it may not have put out any roots at all yet - often takes up to a year or more. It will still grow because it's attached to the parent plant.

Yes agree with Bamboo.

Thanks, B and J. I will take a careful look in spring to see how it's doing rootwise ( it's layered into a small pot) and decide, or ask, what to do then. Never done it before, as I'm sure you can tell.

Once you're sure it has developed some roots I'd wait until new growth starts in the spring and sever it from the parent plant but not dig it up. If the severed plant wilts soon after severing then it hasn't got enough roots to cope on its own with the amount of leaf it has. Trim most of the leaves off and wait until the severed plant is growing strongly and then dig up.

That is the ultra careful method and you'd probably be OK with severing and digging up imediately but if you want to be sure I'd suggest the former technique.

Thank you, Anchorman. Can always rely on getting good advice here.