The Burning Crusade happens in year 26, yes a year after Vanilla wow.
Wrath of the Lich King happens in year 27(yes.. this is silly now)
Cataclysm happens in year 28-29.
Mists starts in year 30 ending in year 31
Warlords starts in year 31
Legion starts in year 32
Battle for azeroth in year 33.
- a 2 year gap here -
Shadowlands is between year 35-36
Dragonflight= year 40, so there is about 4 years between shadowlands and dragonflight
basicly its a year between each expansion in lore, TLDR: our heroes run from one end of azeroth to another as massive threats rise up.
SOurce:
https://wowpedia.fandom.com/wiki/Timeline