Initial Timming?

If the advance is correctly connected to a timed port it shouldn't matter but to be safe you should unplug it. I adjust it for max vacuum that'll allow it to start good. I have ran into a couple cases where the cam was pretty big so max vacuum wasn't until 30 degrees and the starter kicked back so I had to back it off a little so it'd start ok.

You may know this but in case you don't make sure and limit how much total timing you have after you figure out what idle timing you need. If you just adjust the timing for max vac at idle without modifying the amount of centrifugal advance you may end up with 45-50 degrees total timing which could destroy your engine.