I have a lovely specimen of this plant, one of my favourites, and have taken a cutting for my mother-in-law. It is now about 10" high but still a single stem, so I was wondering whether I should pinch out the top?
Not if it has not rooted. They are more normally grown from seed or from self sown seedlings than cuttings.
Sorry, didn't explain properly. When I took the cutting from the base of the plant it was about 2" long, now it's well-rooted & about 10" tall, so I thought pinching the top out might encourage some sideshoots.
I would look carefully in the leaf joints below the top one and make sure that there are buds in them before removing the top.