When will exactly Google Will Ban ?

Hi Guys, I have a doubt reading all these adsense issues, if Google finds someones adsense account is crossing the terms of google, When exactly it will ban his/her account? Will it take some time until some good amount gets into that account ? or it will immediately ban that account? Because if it bans after reaching some round figure like 100 or 500, then its a sort of cheating too from google side isn't ? they should tell the adsense account owner immediately that his / her account is banned from the google as they have crossed the terms of Google.

Can anybody tell me abt this banning system? I am really new to Adsense and want to know about it completely, so that in future i can incorporate adsense in my own Website (http://www.myseotool.com), I alread own a website with adsense integrated, just as per the readings on this forum, but i want to know more details about it. Please help me..

Regards
Evishy