How do I animate influence of follow path I Have been using blender to make/modify objects for 3D printing and now I thought I would try some animation.
I am trying to start the camera moving along a path starting at frame 40.  From frame 1 to 40 it moves via key frames with loc.  Starting at frame 40 I would like the camera to follow a circle path for a couple of iterations.
How do start / stop the influence of the path at specific frames.
I in my googling have seen mention of a start/stop but I am not seeing in properties/constraints.  I see noting to control the constraint in the dope sheet or the NLA editor. (Which I just discovered)
This can be done by animating the influence slider at the bottom the the constraint.

Most interface elements in blender can be keyframed by pressing I while hovering over them.