PR update occurs quaterly but last time it took 6 months. It was in the last week of October. This one was an overall strict update and many many sites lost there PR I was safe though
What you can do is a site:www.yoursite.com on your site every so often to see how many pages google has indexed on your site.
yeh google indexes pages all the time. you don't have to wait for the PR to update before you have pages indexed. google would get nowhere if they did that! imagine building a new site and having to wait til the PR was updated until it was even included in the google index!
Even i have a new Website waiting an opening on the google box office I guess the PR update is due in January