If Japan stays neutral, does the USA even enter WW2? If not, there would be no major building programs at all.
1 February 1939: Specification for heavy bomber with 2,000 mile range, 300+ MPH top speed issued. (B-24)
Sep 1, 1939: Germany Invades Poland. War is declared shortly on Germany by UK and France.
2 December 1939: VLR Bomber (B-29) specification work begun.
January 1940: VLR Bomber (B-29) formal requirements issued.
May 10, 1940: Battle of France and the Low Countries begins.
May 16, 1940: FDR calls for Congress to support construction of 50,000 combat aircraft each year by US Factories.
June 14, 1940: German Troops Enter Paris. Third Vinson Act Signed LINK authorizing 79,500 tons of Carriers, 66,500 tons of cruisers, 21,000 tons of submarines, authorizing a naval air strength of 4,500 aircraft.
June 19, 1940: Two Ocean Navy Bill signed. LINK Authorizing 385,000 tons of capital ships, 200,000 tons of carriers, 420,000 tons of cruisers, 250,000 tons of destroyers, and 70,000 tons of submarines. Authorization of a naval air strength of 15,000 aircraft.
September 11, 1941: United States secretly publishes the "Victory Plan". It somehow leaks to the press, leading to internal witchhunts over who leaked it (I've read the documents about "who the hell leaked this" at the National Archives).
Victory Plan Links:
The Navy Requirements in the Victory Plan (see above links) called for a fleet by December 31, 1946 of:
The big difference is if there's no Pearl Harbor; then everything gets built at a slow, leisurely pace -- I recently ran across in US Navy Bureau of Aeronautics Confidential Correspondence, a paper detailing the original scheduled commission dates for the ESSEX class -- and they're late 1944 and early 1945.
That...got sped up after Pearl Harbor.
As for what could happen in the Original Poster's Scenario:
After a few years of no immediate apparent threats to the US, the USA's paranoia would dial down back a bit, and some of the later ships of the Two Ocean act are cancelled before they're laid down, or some of the older ships get scheduled for retirement -- for example, after BB-66 Kentucky enters service, why keep BB-35 Texas in service, as she's 30 years old and hopelessly obsolete?