It depends on what you mean by “right-a-way”. It’s different for everyone. Some might require more “time” to plan their next incarnation depending on the complexity of the challenges and experiences they want to encounter. Time as we know it is different outside of this simulation. There is not one set time for any given entity.

A belief system held in a previous lifetime might be strong enough to carry on after they pass on and take time to drop away like a belief in a soul sleep or Hell like existence that one goes to after death. This belief will take “time” to drop away before their next incarnation.

Furthermore, an entity might want to wait for a specific “time” period to incarnate where only the lessons they need to learn will exist. For example, if an entity wants to experience what life is like where everyone is connected through social media they might wait until the inception of the internet. Different periods provide different learning lessons which is the reason you see population booms and busts.