The person directly under my management is going to resign on Monday. Should I tell my manager that I'm leaving too, or wait until the following week?

Hi everyone, I need some simple advice. The person directly under my management told me this afternoon that they're going to submit their resignation, so I'll have to inform my manager on Monday morning.

The awkward part is that I was already planning to submit my resignation the following week as well. So I'm not sure whether it's better to be honest and tell my manager about both of us at the same time, or stick to the date I had originally set.

The main reason I'm hesitant is that I'm supposed to receive a bonus in October, and this company is somewhat known for potentially letting people go immediately as soon as they give notice to avoid paying out what they're owed.

I'd be very grateful for any opinions or advice from people who have dealt with a similar situation before.