ERC doesn't take as long to dry as other woods do,but it still needs to be dried out to make a low set bow. Rough it down to floor tiller and let it set a couple months to be sure its dry. Warbow wood needs to be down to optimum dryness to take a low set no matter what wood you use due to the high weight stresses.
Are you looking to make a selfbow warbow with ERC? If so(and your still new to bow building) id suggest planing it down and backing it with hickory or a super thin piece of boo. And in the very least use rawhide over the first layer of sapwood under the bark.