Here's the release schedule for the DLC that has been announced so far. The release dates and number of packs are visible on the Nintendo store. It says Feb 6 for release because of the early access options. Crossroads of the worlds is released in only 2 stages, which suggest that the civs/leaders are strongly connected to each other. In contrast, Right to Rule has 7 packs on 6 different dates.
Edit: the actual content on Nintendos site isn't detailed yet. The only "new" information (to me) is that the fog of war cosmetics change per era. All the non-cosmetic packs don't have an informative description yet. It just says more content that will be revealed later.
Tecumseh & Shawnee Pack Feb 6
Leader Persona 1 Feb 6
Leader Persona 2 Feb 6
Leader Persona 3 Feb 6
Leader Persona 4 Feb 6
Deluxe Cosmetics Feb 6
Founder Cosmetics Feb 6
Crossroads of the World Collection
Pack 1 Mar 4
Pack 2 Mar 4
Pack 3 Mar 4
Pack 4 Mar 4
Pack 5 Mar 25
Pack 6 Mar 25
Pack 7 Mar 25
Cosmetics Feb 6
Right to Rule Collection
Pack 1 Apr 15
Pack 2 Apr 15
Pack 3 Mai 13
Pack 4 Jun 10
Pack 5 Jul 8
Pack 6 Aug 5
Pack 7 Sep 2
Cosmetics Feb 6
Edit: the actual content on Nintendos site isn't detailed yet. The only "new" information (to me) is that the fog of war cosmetics change per era. All the non-cosmetic packs don't have an informative description yet. It just says more content that will be revealed later.
Tecumseh & Shawnee Pack Feb 6
Leader Persona 1 Feb 6
Leader Persona 2 Feb 6
Leader Persona 3 Feb 6
Leader Persona 4 Feb 6
Deluxe Cosmetics Feb 6
Founder Cosmetics Feb 6
Crossroads of the World Collection
Pack 1 Mar 4
Pack 2 Mar 4
Pack 3 Mar 4
Pack 4 Mar 4
Pack 5 Mar 25
Pack 6 Mar 25
Pack 7 Mar 25
Cosmetics Feb 6
Right to Rule Collection
Pack 1 Apr 15
Pack 2 Apr 15
Pack 3 Mai 13
Pack 4 Jun 10
Pack 5 Jul 8
Pack 6 Aug 5
Pack 7 Sep 2
Cosmetics Feb 6