How is the best way to handle percent overlap of routing operations?

We are using 9.0 and creating routings for our manufactured items.  Our manufacturing process has operations that overlap:

Operation 1 - runs for 10 hours.

Operation 2 - starts when Operation 1 is 20 percent complete and then runs for 3 hours.

Operation 3  - starts 1 hours after operation 2 is complete and operation 1 is still running.  Operation 3 runs for 2 hours.

We have planned to use Percent Overlap for operations 1 and 2.  What is the best way to handle operation 3?  We can't use the Percent Overlap because operations 2 and 3 do not overlap - how do we indicate that  the overlap is operation 3 and 1?

Thanks