David Marshall basically had this one:

There are timing marks on your TIICO pulley and timing belt cover -
they correspond to zero degrees BTDC.  On mine they were very hard to
find - I think the pulley mark is actually on the outer crank pulley.
I marked both marks with some white paint and strongly suggest you do
the same.

Then you're supposed to run the engine at 1200 RPMs or so and use your
timing light to get it to the correct timing.  The motronic system has
a 'test' mode that you can put it into if you have a tool that
interfaces with the van's computer (VAG-COM laptop software is what I
used).  In this test mode the computer will hold the RPMs up for you
making life a lot easier - then you just set the timing like David
said by turning the distributor.  I don't know why this Motronic
doesn't do this for you but it doesn't.  I suggest getting the VAG-COM
system, it can also set up your throttle body's basic setting which
you need to make the van at all drivable.  Failing that have a shop
set things up.  If you buy your own tool like VAG-COM you still can't
set the basic CO mixture so going to a shop isn't a bad option.

Good luck,

Damia