Firstly, Quest does not support bluetooth headphones hence this feature should not be used on Quest.
(Bluetooth headphones is known to have significant latency hence Quest officially does not support it. The option of "Bluetooth" in "Experiment" is only intended for Gamepad and Bluetooth keyboard".
We will remove this feature from Quest version in the next release.
Secondly, +0.2 means that your audio is actually ahead of the image.
Suppose the image starts at 0:00 and the audio with its latency starts at 0:02, then you need to adjust the audio -0:02 to catch up with the image.
Hope this info helps.