Often the noise can come from the Guide Bolt (PIN) #4, 5, and 6
On all of my BMWs they have at some time the brakes have managed to squeak, almost regardless of pads, rotors, anti-squeal or not, etc.
There are 2 things to try that work relatively well for getting rid of the squeaking for a while, though it does often come back:
1. Drive in reverse with foot on brake for a good bit, please don't back into anything.
2. Hard stop from a decent speed, without fully stopping (similar to the bedding process).
Note: none of this will help if you have warped rotors as some have found to be their issue).