When does the flu vaccine get updated, and how do I know?

I was at the dr. this morning and she said they're expecting to get theirs towards the end of September. The http://www.cdc.gov/flu/keyfacts.htm site says: When to get vaccinated against seasonal flu Yearly flu vaccination should begin in September, or as soon as vaccine is available, and continue throughout the flu season which can last as late as May. This is because the timing and duration of flu seasons vary. While flu season can begin early as October, most of the time seasonal flu activity peaks in January, February or later.

My healthcare provider's newsletter keeps me up-to-date on new flu shots (which are apparently coming out and the end of September), but I can also find this information on my city's Heath Department website and the local university's clinic's website/Facebook/Twitter.

This isn't "as soon as they become available," but I always go in the couple of weeks before Thanksgiving. The new shot is always out by then and it's easy to remember as part of my holiday preparations, "Oh, I gotta get a flu shot!" And then I've got it before the part of the year where other people are sneezing on you at parties. My county health department also posts about it online, and usually the sign outside their office (which I pass every couple of weeks running errands) says "NEW FLU SHOTS" when the new flu shots are available in the county. I can also contact them to ask about locations with shots in stock, and eligibility in years when supply is tight. That might be the best route for the most complete information.

You can check when this year's vaccine is available in your area at http://www.flu.gov/prevention-vaccination/vaccination/index.html, assuming you are in the US. I got my 2012-2013 vaccine yesterday at a drugstore, even though my doctor does not have it in yet. The pediatrician does have it. The stuff from the state apparently goes to pediatricians, then OBs, and then regular dr offices, but the stores buy it from other sources, so they can get it in right away. It was released in mid-August, fwiw.