Try to get the idle speed down to 500-600 RPM before checking the timing with a light. You're probably getting a little centrifugal advance at 1000. It would also be possible to get some vacuum on the distributor with the throttle plate open far enough to idle at that speed. Ideally, the BB is a good starting point for initial timing. It's not set in stone, particularly since the gasoline quality in the 1950's and what's available today can be very different, and ignition timing needs to be tweaked to the octane rating of the fuel that's available.
If the BB is to the left of the pointer, the timing is advanced a little. Turn the distributor housing clockwise to align the pointer and the ball.
Jerry
