Hi Helga, you can plant them as soon as the plant sheds the seeds as this is how nauture does it. However, if they germinate before Spring, you will need to look after them over Winter. In nature, the vast majority would be killed by the weather etc, which is why most plants produce so many seeds - only one needs to make it in order to continue the species.
As gardeners, we want a bit more control and would like all of our seeds to germinate of course! For that reason, we sow most seeds in Spring so they can grow uninterrupted by harsh weather.
Having said that, the seeds of many hardy perennials, shrubs and trees need a period of cold followed by warmth (known as "cold stratification") before they will germinate. Out of your list I would sow the hellebores now as they benefit from the cold period and are best sown fresh anyway.