I was innocent and clueless in the beginning. I forgive myself, now I know better.
Supta parsvasahita (see picture) is an important pose, at the latest if one tries to practice the first pose of third series vasisthasana. When the leg is not in line with the body balancing is very hard.
My foot is still so far away from the floor, it will take years till it's down. I know that nothing can be forced. Patience, diligence lead finally to success. I repeat this pose, I hold the pose longer than 5 breaths. That's it.
I know that the big toe shall be held. At home I hold the outer side of my feet as it gives me more stability and I can easier pull my leg down.
Both hips shall remain on the floor.
I practiced primary today. My weak points were especially weak today: the vinyasas. Im familiar with the ups and downs. Who cares. I feel excellent now.