That's the way we did ours too. Three times so far. Pole barns here are always done that way. Our last pour was huge and well below freezing temps so we closed the doors and heated the structure with torpedo heaters to help cure it a few days.
Pour it right away though. The only negative to pouring after you skin it is that you might be like me and start working in there on the gravel base, setting things in there, storing things in there.
Looks good.. keep rolling.