How can we effectively test a new app pricing model?

[CommunityDev]

Hello, we have developed Shopify App for "Virtual and In-Person Bookings" and we are trying to update our app's pricing model. We are moving from fixed-price recurring charges to fixed-price recurring + usage charges recurring. We would like to test if this pricing model works as expected before we could release it to Prod. We have also applied Cap to this pricing model. How can we test if our app stop charging user once cap is hit and that we are charging correct amount on bookings they are making? Can we test using test payment gateway?
Also, we would like to know if you will deduct charges from merchants on every booking they get or you charge them at once in the end of month? How we will be paid, do we receive amount collectively in the end of month?

We plan to release this pricing model in 1-2 days. 

Looking forward to your response.