I bet that youi bought these from a Garden center, Irina. They have a very nasty habit of keeping bulbs on sale long after they should have been planted.
I don't know where you live or what facilities you have. To get he best from them this spring I would plant them now in pots. Use a loam based compost and keep the pots in the greenhouse and just moist. Protect them from freezing but don't let them get hot ie less than 10C. You will have to use your judgment of when you can put the pots outdoors so that they don't get damaged by the weather.

follow Bulbaholics advice but I would soak the tubers in warm water overnight then plant.

Thank you both very much! I will definitely try doing it. Unfortunately, I haven't got a greenhouse, do you think keeping the pots in the house would make them too hot? I could possibly get them in +12 temperature at my neighbour's greenhouse but there is quite bright light in it. Would it be bad for them?

Unless you have a cool front porch the house itself will be too hot for the anemones, as will your neighbour's greenhouse at 12˚.

As was said on another question if you want them to flower for a specific day you will probably have to buy pots of them already in flower a few days before the event. It is almost impossible for amateur growers to get bulbs to flower for a specific day.

A friend of ours exhibits at Chelsea, and other RHS shows, the bulbs, and other flowering plants, may have been kept in a huge lightly refrigerated unit, subjected to 24 hour light or 24 hour dark to get them at their peak for the show. It will cost you more but a florist will be able to supply what you need, provided you give them enough notice.