I don't think this is going to be anything you can control.
Office365 Known Issues and Limitations with Triggers
The link shows that "Triggers fire on the corresponding event's occurrence almost immediately in most cases, but there could be rare circumstances when the trigger's delay to fire may take up to one hour."
If your process will have a "Big Problem" if the trigger is delayed by 5 minutes after an email is received then try to think of how to change the process overall. Like maybe an email is not the best way to trigger something, is there an alternative?
Or can the process depending on an immediate trigger be adjusted to accommodate the potential delay?