I have a scene which has many referenced objects in it. I was wondering whether it would be possible to create an animation in the referenced scene and then delay or offset that animation in my main scene?
It is possible, but not terribly straightforward. You may be better off simply offsetting the animation in the original scene before referencing.
When you reference in a file, you are allowed to make and break connections between attributes, and make changes to individual attributes. I believe, if I'm not mistaken, that you can NOT make changes to animation curves.
The first workaround I would try is to see if you can break the connection from the time1 node of the scene to the referenced animation curves. If you can insert a PlusMinusAverage node between time1 and the animation curves, you should be able to add or subtract values to offset all animation at the same time.
Depending on how many animation nodes you have, and how comfortable you are working with nodes and/or scripting with MEL, this may or may not be plausible.