Probably at least two years from Nursery sized plants, if not three. The viticella group seem to settle in quickly and produce a lot of flowers, while the others take a little longer. My C. vit. 'Etoile Violette' was a picture in its second summer. The alpinas and microcephalas are the same, while the large flowered ones need extra time.

Montanas about two years.

it will also depend on the pruning regeime. if you prune at the wrong time you will be cutting the flowering shoots off. so check when they should be done.

thankyou all so much ...I shall be delighted to have them in a few years,thanks for the pruning advice too, which I will keep note of.