Here's another idea.
Take this thread's history of order statements and compile them into a timeline. Then, analyze who got shipped when and observe their corresponding order time frame. The results of this analysis would show the optimum time to actually make a preorder.
Without doing the hard work of the above analysis, I'd suspect that ordering at any time prior to 12:01am PT or for up to approximately 6 hours forward, your orders don't necessarily ship sooner.
Anyone enterprising, there's the beginning of a project for you. Just give me credit when it becomes famous!