As others have said - I assume the delay is 1 - 2 seconds? That's about what it takes for mine to come on when I put the car into reverse. You are right to use the mirrors and rear window, with the camera being an additional aid.
I assume the camera comes on with the reversing light, so if you're looking for a delay you would need to draw power from somewhere else. You probably wouldn't get away with driving the car forward with the reversing light on, even if it is for 5 - 10 seconds. In the "Civic 9g iMid Reverse Camera installation" thread in the "This is How To ... (Guides Only) [9G]"
section of the forum there is a post outlining how power can be provided to the camera without engaging reverse. I presume you would need to do something like that, but I'm sure other more knowledgeable forum members can assist!