I have an audio layer that I'd like to start at the same time as the first keyframe of a mask path titled "Mask 1" on a layer titled "Mask Movement". However, the position in time of the keyframes of the mask path are set to change based on the outpoint of a different layer using the following expression:
target = thisComp.layer("Target Layer");
targetMask = target.mask("Particular Path").maskPath;
In case it helps, the purpose of the audio layer automatically changing its start position is because I'm creating multiple renders that have varying timings, so it would help to automate the process.