Procrastination isn't always a bad thing. When we last looked at my pile of 2 x 4s it was just over a month ago, and the readings from my moisture meter ranged from 10% to 18%. My reason for using this stuff was price – a "precut" (almost 8' long piece) cost $2.38 at our local home center. Good price, but if I tried to work with it in that condition, my finished benches would have twisted as the wood reached equilibrium with our shop environment. Cutting them to rough length and putting stickers in between helped to speed the process. Late last week I was getting consistent readings of 9-10% at the middle and the ends of my boards and decided it was time to proceed.
Without a meter, you're left to guess about how wet the stuff is. One way to judge is by weight; drier pieces are lighter. Wet material will also feel cold and damp to the touch. Comparing new lumber to some that has been around for a year or so will also help you judge.
The lumber did twist and cup a bit as it dried, so I ran all the parts over the jointer and through the planer. The finished size is 1-1/4" X 3-1/4". I came up with this process for building benches and stands for tools about 15 years ago when I was setting up a shop from scratch. Every nickel I could save on shop fixtures was another nickel I could spend on power tools or disposable diapers. Here is the same stack of wood after milling.