User blog comment:Eclectica737/Black Bolt's physical age/@comment-16461120-20190827024303/@comment-1456680-20190904001741

Sliding timescale policy in the Marvel multiverse can be a little hard to wrap your head around. While some canon events do slide up the time scale pulled along by current/recent published stores, other canon events do not slide. For example, the in-universe date that Captain America was joined the Avengers has changed over the years (which is why it is kept vague) but the date of his birth remains fixed at July 4th, 1922. This despite it being canon that Steve Rogers met Howard Stark sometime between 1941 and 1944 and Tony Stark was adopted by Howard Stark sometime in the 1950s, which would make Tony Stark much older than current canon says he is. If you want a an explanation this is really easy to understand (Galactus even says as much on page 16) I highly recommend you read The Ultimates Volume 2, Issue 8, Pages 12 through 14.

So never mind what previous comics have said about when an event took place, all that matters is how far back from the present that event was. Even if Marvel publishes a comic book that explicitly states that a specific event occurred on specific date that does not mean that that statement remains valid indefinitely. Subsequent writers can change the date as they like, either through time travel or retcons or just by dialog that contradicts previous canon. Anyways, the point is that the canon age of Black Bolt is whatever current canon depicts his age as. His age is what the comic book says his age is until the comic books says otherwise. Never mind that a comic book said that he met so-and-so in yyyy-mm-dd, Marvel Time is constantly changing that number (unless it's not). Clear?

Now if you'll excuse me I need to go lie down in a de-aging chamber designed by Reed Richards becasue you're not confused enough yet.