Retime: shifting a clip in time

I'm new to Nuke so please excuse the 'noobie-ness' of my post.

I have a greenscreen shot where I want the shot to start later in time. I've tried a multitude of settings in the Retime node with no success.

I want to be able to see the BG plate before the GS layer kicks in. So far I've only been able to get the GS layer to freeze and then start moving at the frame I want it to appear with the Retime tool. I'm sure there's a workflow to this, but I am unable to figure it out with the controls.

Here's a visual to help explain what I mean:

GS layer: |_________|start________end|
BGplate: |________________________|

If someone can show me a screengrab of the Retime settings, that might help me understand what I need to do. Thanks in advance for your help.