I am new to the Stamblade build, and done some testing on this myself. Can someone tell me if i am wrong or not?

The TL;DR ---- Empower and Precision. Do they count on next skill ACTIVATION, or next skill to HIT opponent?

First off, the Guaranteed critical strike from the Shadowy Disguise, which lasts a couple of fractions of a second longer than the cloak. My question is, does it need to be active on ACTIVATION of your skill (like snipe) or on HIT of your skill. Testing with Snipe tells me that the buff from Shadowy Disguise needs to be active on HIT. So when Sniping from long distance, the flight time will cause your hit to no be crit, even though you cloaked just before sniping. Is this correct?

Next, with the same proc. In the case of Snipe+Ambush, if buffed with cloak before, will the crit be assigned to the first skill to activate, or the first skill to hit opponent? I have had several instances where i feel like my Ambush is actually hitting before the Snipe, due to travel time being slower for the Snipe, than my Ambush. As far as i can tell, the same applies here. It is first ability to hit opponent and do damage - NOT the first ability to be activated. Correct or not?

Next, for the Empower from Ambush;

Same as above basically. My testing tells me it applies to next damage on opponent, and not skill activation. This means i can also do Ambush, Fear, Cloak, Snipe. In this case, my Snipe will both get guaranteed Crit, but also Empower from the Ambush, assuming i can get it off within the timeframes of the Empower buff (think it is 5 seconds for Empower)