All good input above, I myself do not like to crank the motor on the starter ever before the first start. I don't know what BB specs are but with small blocks you can find the points on your balancer to hit the cam bearing oil holes if not running a grooved camshaft.

When people say it should fire right away they mean right away. Even if your timing is out with the carb primed in a perfect world 3-4 seconds and then it fires up is not a unrealistic goal.

But at times crap happens, and ive a 30 second rule of combined cranking time before the intake would be pulled for more lube on the lifters.

Just running the lash pre fire can wipe a good bit of lube off the cam so think of how many rotations can come from 30 seconds of cranking.