If your episodes are all set as day 0 content, iTunes will show them as all having the same date, and may seem to be ordered arbitrarily. iTunes sorts content by date first, and then alphanumerically per date.

In order to control the listing order in iTunes with day 0 episode content, you'll need to structure the title of your episodes in order to have them appear in an order that you prefer (such as starting the title with a date or number.)

Additional keywords: Podcast, sorting