When's best to cut back an evergreen Ceanothus?

They might, they might not, its always a gamble with Ceanothus - but don't do it now, do it in the spring - can't remember if this one flowers springtime, but if it does, do it immediately its finished. If its a later one, you might need to sacrifice the flowers and still do it in the spring anyway.

It flowers in late Spring. What will happen if we cut it back in very early spring, or even late winter - might it show something by Spring? It's in a very prominent position so I'm trying to minimise the time when the area is just bare and woody.

Ceanothus is not a long lived shrub anyway and they tend to be a bit prima donna-ish - if you leave it till spring, when growth is beginning, you'll have more chance that the shrub will cope with drastic pruning - it will flower again the following year anyway, and you may even get some later flowers next year.

mine was getting out of hand so as soon as the flowers had gone over.i cut it back hard, very hard right back to its branches.i was a bit worried it looked dreadfull but now a few months later it looks just fine and as thickened up nicely and it should not need cutting back so hard again for a few years .