When to hack back trachelospermum

[Dingdong99]

I need to replace some rotten trellis which is covered in this plant

I'll have to hack it right down to do this, and it will then look a bit stark until the plant has grown back over the new trellis

Would it be better do this now, (maybe this would be better for flowering next year), or wait until early spring when it's about to have a growth spurt?

Just wondering how much growing it'll do it I cut it now

You can hack it down any time, but I would wait until spring when it will quickly grow again.

Otherwise you're looking at something ugly all winter because it's not going to grow much more now.