I let my wood acclimate to the shop environment. Where I live the environment is pretty stable. In areas where temp and humidity change drastically, I hear folks let the wood acclimate in the room where the piece will eventually stand.
I wait a couple weeks more or less depending on the state of the wood. If I know I am going to have gaps between milling and assembly (like I always do, it seems) I will mill 'close' to final size. I then let the pieces acclimate some more while I'm doing whatever it is I'm doing while I wish I was in the shop (whew, got that out of my system).
I 'final size' the 'close sized' pieces as I get nearer assembly and glue up time. This works for me as I am a hobbyist and have a lot of other things going on in my non-work time. I have been bitten by milling to final thickness and then coming back in 2 weeks to find some warp that I cannot mill out as I am already at final size . . . do-over.
Any sufficiently advanced technology is indistinguishable from magic.
- Arthur C. Clarke