How to use MW-50

[ddmd80]

I have been looking for information about the use of the MW-50 system installed on some German fighters. I have read that you only turn it on at or below 50 percent thottle or you can damage the engine (which I have done several times above that setting). 1. When can I use it? 2. How long can I keep it engaged? 3. At what power setting should I engage it. Any limitations, tips, or links would be great.

Thanks for the help