Google bot

I started my website Kids-n-Fun in may, 2006. It took Google months before my site was visited. In October 2006 the visitors went up from a few (5 to 10 per day) reaching more than 600 at the end of the month.
The number of pages the Google robot visited went up from 100 pages per day to 1200 pages at the end of October.
Look at this graph (from Google Site maps):

My question: What happened first: the increase of visitors or the increase of crawled pages by the Google search robot.
If it is the increase of visitors, how does Google know this, and if it is the Google robot, why waiting for 4 months to really start indexing the pages on my site?
Anybody?