Is there any advantage on a fresh rebuild to already have the no1 cylinder advanced on the timing mark at startup? wouldn't it be a lot closer to the desired initial advance if I set the balancer at 12 degrees before TDC and put in the Dist. at that point? I'm thinking less things to do when we fire it up. thanks.

Sure!

I'd have a lot of initial on a fresh start up, you don't want the fuel/air charge burning as it goes out the exhaust. That would overheat your engine while you are breaking in the cylinders, rings and camshaft.

Should it be 14-16 then prior to turning the key?

Not sure how you can do that though. Hard to know exactly when the spark wii fire by looking at the distributor

Maybe I'm overthink but if you set the timing mark on dampener to 14 Degrees before TDC. Calculated by dividing the inch circumference of the dampener by 360 to get degrees per inch, then set where you want to 14 degrees first. Followed by putting the distributor in set at No1, you should have the initial timing set where you want. Am I wrong?

Sure, that's one way to do it...
I typically set the dampener to 0, drop the distributor in [aligned with cyl 1].
Then rotate the distributor CW a few degrees and tighten the retainer just enough to hold they position.
Once the engine fires, fine tune the timing...

My point is that you can't be that precise knowing when the spark will fire unless you can do something like use an ohm meter to check when the points open. The distributor cap position in relation to the rotor doesn't control the timing. It's the points or whatever electronic ignition you have

Usually it's trial and error getting the distributor in the ballpark where it will fire at all then you dial it in with a timing light once it is running

Like Pete said, (After making sure cyl no. 1 is on compression stroke.) drop dis in at TDC with rotor at no. 1 wire on cap. Then you can get very close to knowing when the spark actually happens by what we used to call spark timing. With hold down just snug, set everything up, harmonic at TDC plus desired advance and rotor to no. 1. With ignition ON, twist distributor slowly until the spark is heard inside cap. Twist back and forth a couple times slowly to be sure you hear the spark right where you want it. A quick way to get you right in the ballpark.