The Japanese woodland poppy has ethereal and not long lasting bluish/lavender flowers. Even so, we go to great lenghts for adding this gem to our woodland garden.
There is no guarantee about the colour of the seedlings; various shades of light mauve, even a whitish/cream seedling are all possible.
Germination: my method involves treating the seeds with GA3 and sowing at warm (under lights in February), in which case they will form sometimes the true leaf right away.
Alternatively sow regularly in late fall, in which case they will emerge the true leaf in the second season. Behaviour similar with Podophyllum hexandrum and Hydrastis canadensis (its closest relative actually). Some seeds will germinate in the second year from sowing. It is very possible that the seeds exhibit combined dormancy, simple and double (the ones that will germinate in the second year).
Depending on how well they are grown, the first flower can appear in the (third) fourth year.