Hi

Its a bit late ... best time is October early November .... but if they need to be moved if me I would wait till all frost etc thawed out is over and not expected in the days to come..... they dont normally flower the following year after getting moved as they are settling in , if they have been flowering well plant at the same depth if not, plant a little higher in the soil.

Hope this helps a little.

Gg

Thanks Gg. It was on my to do list for Oct but somehow got forgotten about! Will keep an eye out for milder weather....

I would add that you should do it as soon as the weather is right. Peonies start into growth (below the ground) very early in the season so the job should be done before this happens.
Make sure the resting bud is ABOVE soil level (I assume we're talking herbaceous peonies). There is no reason why they should not flower in the year after being moved; it is being planted too deeply that inhibits the flowering. I once moved 9 of them, and 8 flowered the following year.