I recently built a test stand for a brand new DA50 for the sole purpose of making sure I knew how to start it easily, and that it ran right before putting it in a plane. Three times I started it and only ran it for less than 60 seconds at lower RPMs with a break in prop (NX 21x8 I had laying around, I won't fly with this prop). The previous poster covered it very well, don't break in this engine or any gasser on an engine stand. They can burn up and besides that it takes so long that it's impractical.

BTW, mine started just the way the instructions said and ran like a dream. Sweet ***** engine.