You want your on-use trinkets on a macro with shadow dance. That's one trinket solved. The other could be a proc, they usually proc within the first seconds of the fight with a duration of 15 seconds. Because of that, I generally pull, get SnD and Rupture up, then proceed into Shadow Dance just before find weakness goes off, buffing my first ambush with the armor pen, trinkets procced and enough duration left on my trinkets to last 8-10 seconds shadow dance. This may not be optimal, but it is close on every scenario, making it a safe bet for prepots and BL on pull. However, if you prepot every time, then you might want to use shadow dance 2 seconds before find weakness expires to get the 1000 agi bonus to last long enough for your clone to benefit from it as well.
Bear in mind that I have no math supporting this.