The schedule for Asterisk releases is visualized below (which is subject to change at any time):
For developers, it is useful to be aware of when the feature freeze for a particular branch will occur. The feature freeze for a branch will occur 3 months prior to the release of a new Asterisk branch, and a reminder announcement will be posted to the asterisk-dev mailing list approximately 60 days prior to the feature freeze. Asterisk versions are slated to be released the 3rd Wednesday of October. The feature freeze for a branch will occur the 3rd Wednesday of July. An announcement reminder will be posted to the asterisk-dev mailing list the 3rd Wednesday of May.
Feature Freeze Announcement Reminder
3rd Wednesday of May
Feature Freeze of Asterisk Branch
3rd Wednesday of July
First Release of Asterisk from Branch
3rd Wednesday of October