Here is a bit on the release date supposedly from soneone within the "inner" ranks. Not exactly sure what that means, but lets take a look at it for it is, a possibility that we may see the Dark Angels codex earlier than what some are saying as April.
Please remember that this is a rumor. I have not heard anything previously about this release date range nor from this source before, so make sure to take with plenty of salt until we can get more information coming.
via Nickolas94 via Warseer
The release date is between 15 January and 15 February u.u Source: friend with an inner informer. This is the reason of so much information in this period.