o.k, I will try this one more time,
question 1:nirvana said they can be grown outdoors some say it wont. will it grow outside? The breeder says it will, if you are on the same or close lattitude as amsterdam, you may have a fighting chance. I am in the central part of BC canada, and there is NO WAY I would put ANYTHING out that early, but a spring frost isn't out of the question. In these parts, outside growers don't put anything out before near the end of May. April 'may' be still too cool, and/or you risk freaky weather outside. Better to germ inside, and start the seedling in a window sill if you have to. Once you get a strong seedling, move it to your outside location (I wouldn't just grow it in the ground, but in a pot so the roots will be in full force near flowering)
question 2:when its the best time to grow outdoors? first signs of spring? Pretty much answered that above. *see question 1.
question 3:in temp under 20C my seeds wont germ right? Your grow bible 4/6 probably told you that seeds and seedlings need warmth. Sooooo...... see question 1 above, and start them inside. Live with your parents and can't grow indoors? It doesn't take anything (except some ingenuity) to create a space to germ and start some seedlings. I will go out on a limb and say, if you just try to "Johnny Appleseed" your 25euro seeds will be wasted. If you have to, start them at a buddies place... start think'n Lincoln....
I hope it works out for ya... part of learning is making mistakes...