No one can. They don't keep a daily list somewhere of users active per day. That would be absurd.

Plus if the person was perma banned, you won't be finding sh!t.

Plus if the posts were all deleted you can't find any info.

Plus the person can't be contacted since they are permabanned.

Plus, there is no way you know they were banned at that exact moment, how the hell do you know that and why is this important?