I'd guess the USN starts of a run of 30,000t long Essex class?
https://en.wikipedia.org/wiki/USS_Oriskany_(CV-34)
They were great fans of large carriers and they could stretch the wording of the treaties far enough for this.
I think a slighty different Vinson-Trammel act in 1934 allows for a greater tonnage of carrier to be be built earlier - with the expectation that they will eventually replace the Lexington and Saratoga and this results in slightly more ships being ordered earlier than OTL with some additional differences.
Then I would have thought something along the lines of Wasp CV-7 is ordered as a fully leaded 3rd Yorktown unit (rather than a Baby Yorktown) after Yorktown (Ordered 1934) and Enterprise (Also ordered 1934) in 1935 following the British ordering the Ark Royal in 1934 and the
Sōryū and
Hiryū ordered in 1934 and 1935 respectively.
I would still have Wasp pioneer the deck side elevator!
Then with further British and Japanese ships principley the 27,000 ton Illustrious, Invincable and 18,000 ton Colossus as well as the '27,000 ton honestly guv'
Shōkaku-class being ordered in 36 and 37 the Naval Act of 1938 (OTL Signed into law May 17 1938) allows for further carrier tonnage and Hornet and Essex are both ordered as 'Essex class' carriers - Hornet to be laid down in 1939 and Essex in 1940 (earlier than OTL)
2 more units are ordered in late 39 and are laid down in late 1940 with a number ordered that year (again earlier than OTL)
Then with the Japanese Empires 1941 Christmas attacks on Pearl Harbour and Panama Canal (Dec 28th 1941) the Ess....Hornet class Pez despenser starts churning them out with the design evolving through war experiance.
The Oriskany is a post war ship and she was incomplete in 1945 and was actually partially 'reduced' in order to rebuild her with all the learnings of WW2 and was not complete until 1950
With the Yorktowns and Essex/Hornet classes being good enough and the latter being a superior carrier to anything the IJN will have I dont see the point!