When to ask for a raise?

My manager let me know that my teammate will be leaving in a few months for personal reasons. As my manager was telling me this, they said “so if there’s anything we can do to keep you, now’s the time to ask” and then they let that hang in the air for a while before moving on to the next topic. My manager and I have a great relationship, enjoy the work I do, etc. The company I work for though is notorious for underpaying its employees, however they do provide excellent work life balance. I have worked on this team for almost 2 years, have received lots of positive feedback about my performance and while we’ve talked about promotions and raises, nothings ever come of it bc my understanding is there’s a lot of red tape and it’s out of my managers hands. I’m currently in the midst of a huge project while will finish up a few weeks before this teammate leaves. So my question is: How and when can I use this opportunity to finally get a decent salary bump? Or is that a trashy move to take advantage of?