Good Morning/Afternoon/Evening

I had a chat on AIM with someone that went like this.
It's mainly one-sided and I deleted her messages from this.
I want to know your oponion on the subject matter though.

[16:46] agua 1989: good evening
[16:46] agua 1989: um.. afternoon
[16:47] agua 1989: afternoon, right? evening is much more near dusk I think.
[16:47] agua 1989: and generally goes in to the night till one
[16:47] agua 1989: than it's morning.
[16:47] agua 1989: 24/3=8
[16:48] agua 1989: yeah? morning, afternoon, and evening
[16:48] agua 1989: I'm putting to much thought in to this, is what I'm getting at.
[16:48] agua 1989: and if afternoon starts at 12:01
[16:48] agua 1989: than evening starts at 8:01
[16:49] agua 1989: and morning starts at... 4:01
[16:49] agua 1989: yeah
[16:49] agua 1989: can't add good night, that's a departure statement.
[16:49] agua 1989: Well, that's done.

Ok....