Race instructions
I've actually found that the instruction manual (downloadable from the raceguns.dk site) includes quite detailed instructions for setting up the timing. I'll check out the name of the document I've got from them and get back to you.
As each marker is slightly different (weight, friction, pressure, loader speed etc.), it is very difficult to suggest one setting that works for all. The instructions from Race go through setting it up and testing it out (a couple of sections require a box or two of paint to make sure it works).
It takes time to find the correct settings for your marker (I'm currently using the factory default at the moment... just until I get a few upgrades).
Good luck.