from After Effects Help:
"To go forward a specific period of time or number of frames, click the current-time display, and then enter the plus sign (+) followed by the timecode or number of frames to advance. For example, enter +20 to go forward 20 frames or 1:00 to go forward one second. Precede the value by the minus sign (-) to go backward. For example, enter +-20 to go backward 20 frames or +-1:00 to go backward one second."
ah ok cool, had checked google and maual but didn't hit the right term,.