I have placed a jumper on A & B while setting the time. When I removed the jumper the timing marks moved off the scale to the left. Is this the proper setting?

Yes thats correct , the timing marks won`t line up after your out of the field service mode ( a&b grounded. ) They should line back up when grounded again correct ? If so , you did it right...

And for those who wonder why that is:
The ECM advances the timing many degrees under certain engine conditions. Idle is one of them. By grounding out the diagnostic pin of the ALDL line, you disable that advancing, so the engine is running with only the base timing. This is what you must set.

The engine has no way to know if the base timing is right or not. If you change the base timing, it will assume it's still at stock and add in the advance that it thinks is right. If you have the base timing advanced much past stock, this will result in the engine knocking.