Hi there @Decision making time frame,
Welcome to the Community! Love the user name by the way.
This is a great question! At this time, we don't have any reporting on the average time or timeframe between a subscription event for a new sign up, as we can’t track anonymous website visitors , and someone's first purchase.
However, you can create a few segments to identify those who have placed or have not placed an order since subscribing. You can use different segments for different time windows (30 days, 60 days, 90 days, etc), to see how these segments of customers evolve overtime. For example:

We do know that users want to measure segment reporting and this is a feature we are readily working on!
Thanks for participating in the Community!
-Taylor