how many hours before I need something do I have to start being nice?

Garbanzo's behavior was dreadful this morning, just plain awful.  At some point his sister asked me if we were going anywhere today.

Me: No.
Tater: I thought Garbanzo had Basketball.
Me: Well, we not going.
Garbanzo: (bursting in): That's not fair.
Me: What do you mean?
Garbanzo: Yeah, I know I'm being bad, but I was planning on turning it around in time to go.
Me: Well it doesn't work like that.
Garbanzo: Why not?
Me: You can't treat people badly and then shape up when you need something from them.  That's using people. It's not okay.
Garbanzo: Well, what time should I have started then?
Me: Started what?
Garbanzo: Being good.
Me: Well, when you got out of bed would have been a good time.
Garbanzo: No, I mean, how many hours before I need something do I have to start being nice?