Best way to assign a non action based Journey to a large subset of our employee population?

We need to assign a Journey to a large subset of our employee population. The Journey needs to be assigned on 8/1/25 and then expire on 9/30/25. There is not a corresponding action that we can utilize to trigger/assign the Journey, it is date-based (need it assigned on 8/1/25). What is the ideal approach to do this? In addition, we want to be able to utilize automatic communication to those the Journey is assigned to (Nudges/Reminders/etc…). The idea would be to have a Nudge/Reminder/etc… occur as soon as the Journey is assigned, another halfway to the expiration date, another one