Wood anemone (Anemone nemorosa it is here - hvitveis in Norwegian) is one of my favorite plants. The wild ones start flowering late March/early April and continue through May.
In the garden I have several forms, here are three:
The light blue (or what you will call that color) is a seedling of A. nemorosa 'Robinsoniana' I think. It pops up many places in the garden. The cream yellow is a cross between nemorosa and ranunculoides. I had to buy a new one, the big clump I had was conquered by lesser celandine (a weed here). The yellow is A. ranunculoides, a Norwegian native though not common. I have three distinct types. They differ from nemorosa in color and in having more than one flower pr stem.