Given the six-week schedule for Firefox/Thunderbird releases, Firefox 17 is scheduled for release on November 20th. Six weeks from that date would have put Firefox 18 release date on January 1st, 2013. In the past things usually slow down with Mozilla from around Thanksgiving to New Years and especially during the week between Christmas and New Years. Mozilla has announced they are going to extend the support cycle for Firefox 17 to 7-weeks and likely will release Firefox 18 towards the ‘middle’ (January 9thish) of the week of January 6th, 2013. The schedule will return to every six-weeks again with Firefox 19 which be released now on February 19th instead of February 12th, 2013.