Fiddlerman said
I think they are great if you are at that level. They promote so many advantageous techniques such as finger independence and keeping fingers down while using others. Positions become more natural. Finger stretching and chord intonation improves.
However, these kind of exercises can be torture if you begin too early.

What do you think is the right level to start applying these exercises?  What should you be able to do already?  Does Dounis have any recommendations about how skilled a violinist should be before using his exercises? 

Fiddlerman said
If you can read his exercises already, you are at the right level. If you need to struggle through them, you might want to wait. I'm not against students beginning difficult etudes, studies or works too early, just feel like it can be psychologically challenging to shoot too high too early.
Baby steps works better for many.

That's a good point.  You don't want to assume any false progress or face any false disappointments in learning anything.

Maybe a spirit of play is the best way to approach advanced material if you have limited experience or technical skill.  If you don't take such a leap too seriously, then you don't risk any self esteem by making the effort.  And even idle play can provide educational opportunities and advance skills too.  There is a risk of picking up some bad habits, but play should not replace serious study in the basics.

That's my attitude in many ways and I'm trying to lay out strategies up ahead to keep my anticipation up, that's all.  And also, my study is entirely self guided, so absent a program, figuring out a lesson plan is my job alone.