Pathfinder 1E Taking 20 with Sleight of Hand

[Vegepygmy]

From my read of the skill description, it appears you should make the SoH check at the same time as the opposing character makes their Perception check to find the item. That being the case, you don't have the opportunity to take 20.

This is correct. You should never be able to take 20 on an opposed skill check.