By default, Chargebee collects the setup and subscription fees only on subscription activation. If you’d like to collect the setup fee for a trial, you can use the Auto Addon option. The Auto Addon option allows you to group addons with a plan so that the addons are automatically added to a subscription when the plan is selected.
To collect a setup fee at the beginning of the trial, you can attach a non-recurring addon to the plan and choose to apply it to the “subscription-trial start” event. To do this, follow the steps below:
Attach a non-recurring addon to the plan:
First, create a non-recurring addon with the setup-fee amount and then navigate to the plan page to which you’d like to attach the addon.
Note: If you are PC 2.0 then create a Charge and attach it. Click here to know more about adding charges.
Under the addons section, and choose the “Restrict Addons” option and select the non-recurring addon for the setup fee charge. To select the event when this would be applied, choose the “Subscription trial start” under the “Charge customers on” option.
The addon will be automatically applied to the subscription when the plan is selected. Here’s a gif of a plan with the setup fee addon attached to it
Note: The setup fee is a one time payment. If the customer cancels the subscription when in trial and wants the setup fee to be refunded then you need to manually refund the amount. Click here to know more. 
How do I set up a paid trial for my plans, in Chargebee?