Primer - wait to block?

I am ready to start painting my 71 Duster. I am reading the data sheets and have a question.

When I was glancing at different pages, I saw that on the Eastwood website, it said WAIT 5 DAYS FOR THE PRIMER TO DRY BEFORE BLOCK SANDING.

That is the only place I have ever seen that. The page was not specific to exactly which primer they are referring to.

I am using the Acme Finish 1 primer. FP410 2K HS primer.
I see now the data sheet says, to sand: 2 hours for air dry, and upon cool down for force dry and short wave infrared.

I have painted the car before and never worked as good as I liked. So this time I am paying close attention the instructions I can find. This time, belt and suspenders

Am I correct that I should block sand by hand rather than a Random Orbit Air Sander.