Delay period between blanking screen and sleeping computer

[martreumer]

I really like the screensaver, but am missing a small feature (feels small, could be wrong about that). I would like there to be a period between blanking the screen and sleeping the computer. So for example have the screensaver start after 5 minutes and blank the screen after another 10 minutes. But wait for another 15 minutes to sleep my computer.

If I understand correctly right now there is no way to add that 15 minute delay between blanking the screen and putting the computer to sleep right?