Too little, too late / A bit late, isn't it?
Ironic expression used when help or action arrives much later than needed. Implies the timing makes the gesture useless or frustrating.
Now that everything is broken you offer to help. A bit late, isn't it?
—I'm letting you know there was a meeting. —A bit late, isn't it, it's already over.
Too little, too late. I've already made the decision.