Make sure to disconnect the idle stabiliser and put the two plugs together
before trying to time it. Otherwise, the idle stabiliser will try to move
your timing around all over the place and you can't do it. If you can't get
it to idle that way, you might need to turn the screw on the throttle body
until it does idle.

If you advance the timing a bit, you get better power. Try 7 to 10 degrees
BTDC. I've heard it said that you might not pass smog tests this way, however.

The Bentley manual is pretty thorough. Westfalia.org has some good tips as well.