By now you've likely discovered that your arrow keys can be used to nudge footage in the Comp Window. Did you know that you can nudge in the timeline as well? Selected layers can be slid forward and backward from the keyboard.
To Nudge a layer earlier, press Option+Page Up (Alt+Page Up).
To Nudge a layer later, press Option+Page Down (Alt+Page Down).
To Nudge a layer to even earlier frames , press Option+Shift+Page Up (Alt+Shift+Page Up).
To Nudge a layer to even later frames, press Option+Shift+ Page Down (Alt+Shift+ Page Down).