The best time to lift, divide up and move snowdrops to new locations is when flowering is nearly over. Lift a clump in the green (i.e. with leaves) with a spade, remove any weeds and split the clump into smaller parcels of say 6 bulbs for planting elsewhere.
Once the weather improves get cracking with your clump forming herbaceous plants which have expanded, overcrowded and got too big. Dig up the whole clump while still dormant and quite literally chop it up into sections with a spade. One clump to plant back in situ, one or two clumps for somewhere else in the garden, and the rest for sale on your National Garden Scheme Open Day, Village Fete, Charity Auction.
Plants you can deal with in this way:-
Primula ‘Wanda’ will start to flower here and the first primroses (Primula vulgaris) will attract comment. More harbingers of Spring!