Firefox 22 was released on June 25th, so the week of August 6th for Firefox 23 would be consistent with Mozilla's releasing updates every 6 weeks.
Thunderbird isn't being maintained except for security releases, so the official releases have been for 17.x versions. If there is a future release of a fully updated Thunderbird, it will probably coincide with the next full Firefox ESR release. Development of Thunderbird has been relegated to the back burner.