I've been setting the start date for some subscriptions to a certain amount of days in the future, in order to setup a free trial system for some clients. So, for example, if a product subscription has a 30 day trial, I'll set the start_date value for that subscription for 30 days in the future. That way the customer doesn't get charged until 30 days later.
However, I've recently noticed that the next_transaction_date for these subscriptions is getting automatically set to 30 days after the start_date, for a total of 60 days before the next_transaction_date.
So my question is: will a transaction take place on the start_date, or will it wait all the way until the next_transaction_date? If the latter is true, then all I need to do is set the next_transaction_date accordingly. But I wanted to ask first, because if the former is true, then setting the initial next_transaction_date to be the same as the start_date, might cause a double charge, which of course would not be the desired effect.