I ran through the first section or two of this timeline and have some suggestions & additions I thought I would throw at y'all. I won't be upset if none of these are implemented lol. If there are some predetermined standards that some of these ideas go against it would be helpful to know so I do not annoy by suggesting similar things in the future. The work done here is very very impressive and these comments are only meant as helpful additions. Note: all my TV flashback times here do not cut out the beginning credits so if you would like to adopt these edits I can go back and get the most accurate time stamps.
Eternals: 0:00:00-0:00:41 should be the first thing on the timeline in my opinion (~13,800,000,001 BC). While I understand it is just text it does expliciity reference the big bang/creation of Infinity Stones. Additionally I believe that Arishem explains that the deviants were created millions of years ago for the later paragraphs. This could also be split more specifically ex. (0:00:00-0:00:23) @13,800,000,001 | (0:00:41) @???,??? BC | (0:01:00-0:06:40) @5,000 BC (As placed)
Additionally, a fun touch for the beginning of time would be using (0:13:19-0:13:59) (Wong explaining the big bang) from Infinity Wars and labeling it Audio Only.
Eternals: Just at a first glance it seems like the times used here are all ~2-3 seconds off from Disney+'s times. Dunno if that's worth a fix or just something on my end.
Guardians of the Galaxy (Vol 1): 57:44-57:55 & 58:00-58:07 Completely understandable why this wouldn't be cut out, since it's showing a screen of the events millions of years ago in 2014. I would argue that it should be included just like the first 30 seconds of Black Panther Story of Home is included in its correct location. It's a story being told in 'modern' times but showing visuals from millions of years ago, Black Panthers flashback is just more clean so this is pretty subjective. If you do decide to make this change, a thousand years go by in between Eson destroying the planet and the cosmic beings holding the stone.
Runaways: Missing flashback from Runaways 2x13 from 1:20-2:45 an animated flashback of the origin of Xavin. This can be placed 11,000 years prior to the story dialogue from Runaways as reference. From 2:45-3:10 is a pseudo flashback lining up with the hole opening in a previous runaways episode. I don't have that lined up in my timeline but I can do some digging if y'all would like.
Black Panther: Why cut out the first 30 seconds but none of the other intro? It can be grouped into sections revolving around ~6,000,000 years ago for the first black panther. And then ~2-5 second snippets for multiple time periods after. I understand that none of the first couple minutes are actual visuals of what happened but I would argue to either include all of it split up or none of it split up.
Agents of SHIELD: 3x19 Failed Experiments. That flashback is placed at 3,500 BC using Marvel Wiki as reference.
Failed Experiments | Marvel Cinematic Universe Wiki | Fandom (Idk how much the wiki is used as reference, but sometimes what they use as reference for their dates is satisfactory in my opinion)
Separately, there is a flashback of Pachakutiq/Sarge first taking the form of Coulson in AoS 6x11 . Dialogue in AoS places this thousands of years ago and therefore should be cut out in my opinion. Rough time for flashback is (26:35-27:00)
Echo: 1x1 Chafa Flashback: This is a subjective edit: The creation story was created and based from the Native American Choctaw creation story (Ref: The Making of Echo). The Choctaw creation story is based on the Spiro mounds which according to the old academic text I read quote "Spiro Mounds, Oklahoma's only archaeological park, is made up of 140 acres encompassing 12 southern mounds containing evidence of an Indian culture that occupied the site from 850 A.D. to 1450 A.D." Since the historical evidence placed the first evidence of Choctaw Native Americans at 850 AD I have placed the Chafa origin flashback at the same point, as the concept is they were the first Choctaws. Again it is subjective but I would at least move the flashback between Eternals 400 AD & Thor Ragnarok Chapter 12.
Cloak and Dagger: 1x10 Colony Collapse: First flashback is in ~1650, second is in 1793, third is in 18:15 (Correct)
Divine Pairing | Marvel Cinematic Universe Wiki | Fandom (See AoS wiki note)
Iron Fist: 1x10 There is a recording of a previous Iron Fist in 1948 that is shown between 0:16:45-0:17:15. While some of the recording is shown as on a TV screen there are points that are shown as the entire frame of the screen, suitable for placement in 1948.
If any of those don't make sense I can probably elaborate.