The ability to customize the "Purchase options order" for the subscription widget is now generally available! 

Select whether you want the Subscription option or the One-time purchase option to be listed first on the product page. 

How do I make the change? In the top navigation bar click the wrench icon and then click the "Subscription Widget" link. On the Subscription widget settings page navigate to the "Purchase options order" select the order to be "One-time + Subscription" or "Subscription + One-time".

Can I preview this before I save? Yes! The "Subscription widget preview" on the right side of the page does reflect the option selected in this setting, so the changes can be previewed in real-time before anything is published!