I play Control Magic on my opponents Ajani's Chosen. Do I get a token?

The details are important. When is the trigger event, and when does the creature change controller?
Rules references would be great.

Hi,

Yes, you will get the trigger. When Control Magic resolves, it enters the battlefield attached to the Chosen, and (because it's attached to the Chosen) you gain control of the Chosen. The Magic does not enter the battlefield, then becomes attached to the Chosen. After the Magic has entered the battlefield, we check to see if anything should trigger based on Control Magic entering the battlefield. Since you control Ajani's Chosen at this point, Ajani's ability will trigger and you'll get the 2/2 token.

Nathan Long
Magic Rules NetRep