I guess another way to say it is:
I’m wondering how to begin and/or end a layer at a given point in time.
EDIT – Actually, come to think of it… that’s not another way to say it… that’s another question entirely!
How do I begin or end a layer at a given point in time? In AE this would be easy, just slide the layer end to where you want to cut it off. In C4D… pretty hard.