New Post: Getting Item ID Before Document Saved.

Re: Understanding of how you are storing data
What I don't understand is the approach you are taking for storing the relationships of orders to products... or products to Orders.... can you elaborate on that? is it rows in a list? data in a column? If data in a column - where? the Order list? the Product List?
If you can describe your list setup and column of each, I (or several that "listen" to this SPSErvices forum) can help.

Re: New Button intercept
You could overwrite the NEW button on the page with javascript so that when the user clicked on it, it would not redirect to the NEW form... but... that button can appear in a few places. I Think the easiest path is for you to customize the NEW form and

1. Hide the UI from the User
2. Using javascript/SPServices - create a new item. This returns to you the new order created.
3. Use the ID of the new item and redirect the URL to the Edit page.
   

Customizing the NewForm is a "catch all"... regardless how the user got there (ex. they typed the URL, they clicked the NEW button on View... they clicked the NEW button on a DISP form), it all lands on the NEW form and thus your customization is assured to kick in.

RE: Your statement - "i tried Redirecting in the new form and it does it pretty quickly. I haven't done the item create yet, "
So I'm not sure what you did here... I'm assuming you invoked the NEW form for the Orders with a source= defined and then clicked CANCEL? because if you clicked OK, the new item should have been created (your sentence said you did not yet create the item).