Edit: In response to deleted posts...
I've got plenty of stories about initial timing. Here are two:
A good friend of mine got a custom cam from Vizard (262 on a 108, IIRC). He calls David up and says,
Hey, this cam isn't at all what I wanted. It sounds like a damn race car.
David asks him where his timing is set.
8*, just like the book says.
David asks him where the distributor is hooked up.
Umm, to the port on the carb for timing.
David tells him to forget all of that stuff. "Set the timing at 20* and make sure your distributor is hooked up to the manifold."
He said it was like a whole new cam. His exhaust guy who was there for the build wouldn't believe that he hadn't installed another cam. Night and day difference.
Another friend of mine (the guy in the Corvette video I post on occasion) installed a new cam and called me up asking why the thing sounded like a sprint car and died every time he dropped it into gear no matter what the idle speed was.
I asked him where the timing was set.
At 8*, just like the book calls for.
I asked him where the distributor was hooked up.
On the port for the distributor, just like the Holley pamphlet says.
I told him to consider 15* an absolute minimum and don't be remotely scared to approach upwards of 25* on that engine and hook it up to manifold vacuum.
He calls back a few minutes later revving the engine and sent me a video of a burnout within the hour.
So yeah, initial timing is extremely important. It sets the baseline that the centrifugal and vacuum advance begin from. It's cam and altitude sensitive.
Enough typing. Me go now