We've just rolled out two new features related to your sidecart: A "Ship As Soon As Possible" button, and the ability to put non-Paizo preorders and backorders into your sidecart.
If you have items in your sidecart that could be shipped now, you can click the "Ship As Soon As Possible" button to get your order processed without waiting for the next subscription product to arrive. You'll be given an opportunity to verify the shipping address, payment method and shipping method before the order is finalized. Note that replacement items (i.e., Paizo is paying for the shipping) can't be shipped like this -- they need to wait for the next subscription shipment. (If you really, really want your replacement items shipped immediately, contact customer service and they can process your order for you. But you'll pay for the shipping for those items.)
A couple months ago we started letting you specify during order checkout that you'd like the items in your cart to ship with your next upcoming subscription shipment. At the time that was limited to products available immediately from our warehouse or our distributor, or Paizo preorders. We've now extended that to non-Paizo preorders and backorders, so you can get that new Order of the Stick book and get it in the same package as your subscription shipment when it comes out.
[edit] I guess I should point out that the "Ship As Soon As Possible" button will appear on your My Account page, in the box labeled "Sidecart." If you don't see the box, you either don't have any subscriptions or you don't have any products waiting to be shipped with your subscription. If you do see the box, but don't see the button, you don't have anything that could be shipped right now (i.e., they're all upcoming preorders, backorders, or replacement items).
Cpt_kirstov(Pathfinder Charter Superscriber; GameMastery Maps Subscriber)
Wow! Thanks Gary and Ross! looks like this will solve a bunch of the issues people had with the bestiary shipments!
How do I change my current pre-ordered items to (now) ship with the next subscription order? I don't see that option available as a post-ordering option, but I'm hoping it's possible :-)
Basically, anything I currently have pre-ordered in my order history -- I'd like to just ship with my next sub.