How do you know when its ready to pour?

[Designated Dave]

I am building a 24x32 polebarn. Before we built the shell we scraped the topsoil off, drilled the holes for the posts, and then put about 6" of sand on top of the dirt just to keep from it getting to muddy in there while building. Here comes my question. I am just about done bringing the rest of the sand in (the building is built on ground with a slight slope) On one side the sand is about 12" deep and I have about 18" on the other side. I put it in in two lifts compacting it between and after. Should I be ready to pour, or should I wait to see if there is any settling on the deeper side. That and does the sand need to dry out any before we pour. Its not wet (like soupy wet), but its not dry either. (it did pack well) I will be putting a plastic moisture barrier between the sand and concrete. Thanks in advance.

 

[rodnok1]

There is alot of debate about the placement on moisture barriers, do a search here on it, most will recommend one, just the placement varies, usually not directly below the concrete because of cracking/curling concerns from water only evap from the top.
The sand can be moist but not so much it allows it to move around. It's more important the soil is evenly compacted, so any settling is uniform. You didn't use any stone under the sand?