I would have hoped that they were already planted, Guest.

They say "in the green" is best.....which usually means just as the flowers are dying off..........

Galanthus grow from small bulbs that do not like to dry out. They should be planted right away. If your bulbs have been allowed to dry out, I suggest soaking them for a couple of hours first

Do you have galanthus bulbs sitting out of the ground now? If so get them planted immediately. If you are wondering about when to plant bulbs you don't yet have do not buy bulbs that have been allowed to dry off as Janey says buy them 'in the green' i.e. they will have been dug up when the leaves are still on the bulb. Get them into the ground a.s.a.p. and do not expect to do much for first year as the move will have stressed them.