POR-15....How long before...

I sealed up a tank today with POR-15. I won't be putting gas into it for a while. That's not the issue.

I want to start sanding, prepping, painting the outside. Sort of a ratty, patina type thing. How long before I should put the (old, sacrificial) petcock in and screw on the cap? Would it hurt anything to not let the POR-15 liner "breathe" while I worked on the outside?
It's been in there for about 3 hours now and isn't dripping, but it is still "soft".

How long should I wait before capping up the tank so I can wet sand, prime, etc., on the outside?

What does POR15 say? I last used it years ago and remember it drying quickly. Its very thin like paint.

They just say to wait 96 hours before adding fuel.
I won't add fuel for weeks. I just don't want to mess up the curing process by capping it off to start bodywork. Maybe I'll give it a solid 24 hours. I have a fan blowing across the filler neck now.

96 hrs is likely the complete cure time plus some for insurance. Just follow the directions and let it sit until it's ready. Has to be something else to work on until the 96hrs is up...