How to trigger task based off start date

Summary:

How can I activate/trigger a task in an onboarding journey based off start date? This would enable a notification to be sent in a timely manner. Currently, we could complete 9 out of 10 tasks in the first week and then manually remember that the 10th task is due, 3 weeks later, i.e. on start date.

Content (required):

Customer has an onboarding journey that has tasks prior to the start date and tasks on the start date. During pre-day 1, the activities will be completed by a Pending Worker. Then, we have a task for the manager to confirm that the employee actually turns up on said start date. IF they do, then we convert the pending worker to worker and the second load of tasks now becomes available by the employee (new role, from Pending Worker, updates to Employee).