After I signup a customer, there is a variable (but finite) period of time during which a number of setup operations occur. This period is limited to 2 months.
This variable period of time is not a trial, but really a setup time during which the system is not 100% usable. During this period, the customer will be asked to provide payment information to be used on activation.
When the setup completes, the subscription is activated and the first payment is processed.
Is this flow supported?
Can the payment information be obtained upon creation of the future subscription?
Can the start date be changed to current time, causing order creation, payment to be processed, billing?
Yes, this flow is supported in Chargebee.
You can create a plan for the service you offer and every plan will have its own hosted page URL. You can pass the subscription [start_date] parameter to the plan specific hosted page URL so that the subscription does not start immediately after the customer checks out. This parameter subscription [start_date] is passed if you want to start the subscription at a future date instead of starting it immediately.
Here's a sample URL for one of your plans:
Once the subscription is created, it will go into "Future" status.
As you aren't very sure of when the setup process will be complete, you have an option to push the subscription's start date further to a future date using Change Start Date option by going to Subscriptions > Change Start Date.
When your setup process is complete and you are ready to activate the subscription, you could Change Start Date and by clicking "Now" in the calendar option, the subscription will move to activated state and invoice will be generated.
Hope this helps!