Do you mean salvia hot lips if you do the best time is early spring. They will take a hard prune I cut mine down to about 6 inches from the ground

If it is very large you can trim it by a 1/3 now and use the trimmings as cuttings. then when you see new growth in spring [April here] you can then prune it further. The top growth will protect the lower buds from any frosts we will get.

Salvia Cherry Lips is similar to S. Hot lips by the way. I do not think it is quite as hardy, so I would suggest leaving hard pruning until spring as Seaburn suggests.

Salvia Cherrylips does seem to be more tender. Friends in Beverley have it as well as Hotlips and always take cuttings late summer as they have lost the original Cherrylips plant a couple of times now.

Thanks so much to everyone for all the great advice! I appreciate your knowledge and feedback.
Fab info as always. :-)