Not covering for Mitch, but it does seem that within the wheel industry as a whole, delays are par for the course. It is very rare that I have a supplier send out wheels early, it seems. I agree, if you were given a special time of delivery consideration in exchange for your order, that should have been fulfilled. Most vendors, like myself, would never accept terms beyond our control.
I prefer to over-quote the manufacturing times of wheels. It is better to be honest and let the customer know that they could be waiting 6-10 weeks, rather than promise an earlier delivery and catch grief later when the wheels run late. If they show up early, that is just an added bonus.
BTW, Mitch cannot respond to this message personally. His account was banned here.