Glad to see that the pageviews didn't dip after launch.

Question: how did you initially get advertisers? I'm assuming that the $500 ($462 last month) is from your sponsors adhering to something like this:

  monthly fee = pageviews * $X.

Did they pay anything up front, or do you charge at the end of the month? Feel free to not answer if these questions are too prying. [I'm launching a small (side project) content site soon, so I am curious]