It is now possible to use trial for fixed day scheduling, e.g. billing on the first of every month. If trial is used the subscription will be in trial and billed at the end of the trial period. The billing at the end of the trial period depends on the configured partial period handling. If proration is used, a prorated invoice will be made for the remaining billing period until the fixed scheduling day.
As an example consider a subscription plan with billing every first of the month and a seven day trial period. If a customer signs-up on the 14th, the trial will run until the 21st where the customer will be billed prorated for the period 21st to end-of-month.
To configure trial on a plan go to: Configuration → Plans → Create/supersede → Trial.