Welcome to the Asana Community Forum @Christian_LaCour
So as it stands for recurring tasks when the new task is created the due date of the subtasks stays as per Recurring tasks and subtask dates
Now for your case a possible workaround could be to think of a specific rule trigger such as tasks added in a special section or depending on a specific custom field selection, or task assigned to somebody specific and based on the trigger it will then add the subtasks
Now bare in mind that rules on subtasks won’t work yet and setting up time for subtasks you can only select due in so that means you would have to assign the main task with an earlier due date so the subtasks are allocated accordingly.
And then when an action is done on the subtask you could move the task to another section so a new rule triggers to update the main task due date or you just update it.
Another option is using only main tasks and working with stages or use a tool such as Flowsana which has more rule features for subtasks also: Applying rules to a subtasks using flowsana - #4 by Phil_Seeman