I mean the answer is that you just feel it out. 1 month is soon enough to wait, 2 months is gray area, 3 months is probably fine. And if it's a huge vest, then you give more leeway.
You're not appealing to some objective rule here. You're thinking about what would look like shitty behavior to the rest of your employees.
Firing people gracefully is a really, really important part your relationship to your employees. It's about whether people feel like they're being respected as professionals or abused like they work in a sweatshop.
I take the point of view of the employees who have been wishing that their underperforming colleague was fired already, and would rather the company not spend money (which could be theirs) on someone who's dragging down the team.
What about that scenario? Not every underperforming employee is the case that you imagine.
Come on, they know that money won't be theirs. I have never heard of a corporation saying "we'll fire this person and distribute their next vest to the rest of the team"! No, it goes into some generic pool. First priority for RSUs is usually new hires.
I can definitely see wanting someone gone. Been there. But everyone probably hopes they get a soft landing and find a job that suits them better (unless the person's a huge asshole, then maybe not)
You're not appealing to some objective rule here. You're thinking about what would look like shitty behavior to the rest of your employees.
Firing people gracefully is a really, really important part your relationship to your employees. It's about whether people feel like they're being respected as professionals or abused like they work in a sweatshop.