Mac - I just don't see it easily.
Say they decide to wait. That means that almost certainly they're not at war with China etc. and their war-party that couped the government turned out to be paper hawks. By the time the 50s roll around, the competing interests of the USSR and the USA within the KMT government are so deeply entrenched that to go to war with China is to invite an instant smackdown from both. It would be really really hard to justify as well; it's not an opportunistic attack that later becomes a war of desperation as OTL, it's deliberate suicide.
Say they are at war with KMT on schedule. That means the problems that forced them into an early war are still all there - allied embargoes, expensive occupation, manpower drainage, and no oil and no rubber.
They have to get those resources to defeat China, and to get them without someone trading it to them (and to be honest, can they even afford them in the quantity needed?) they have to attack someone. The Dutch, probably, but that means the English and the French too. And the Americans, who were looking towards containing Japan for some time.
Therefore schedule similar to OTL.
Say they manage to get some kind of neutrality from the US in regards to Chinese meddling and manage to get Chiang to ally with them vs. the Soviets, or something like that. Chiang would be in trouble and very likely the Japanese lose their mainland Empire quite rapidly. If they go for quick peace, and decide to try again in '54, the Soviets are probably indirectly controlling China anyway, so it's suicide, and doesn't fulfil the conditions of "Japan vs. World". Early China+USSR vs. Japan is even worse, though it makes the Soviets potentially weaker in the pacific in '54 (Chiang is coversely stronger).
The only thing I can think of is:
1. The USA ignores China and picks Japan, perhaps in response to greater Soviet successes/meddling in China; moreover, the Americans are supporting the Japanese with oil and rubber and whatever else they need through reasonably cheap trade deals. That way the Japanese can declare opportunistic war AND not be forced to attack the WAllies early.
At the same time the USSR has to be preoccupied with something else (Germany?) AND China can't be an outrightly communist state (USSR has to fight for them to save face). Perhaps Soviet interventions in the 20s and 30s lead to some kind of permanent results, the KMT's left wing is not purged, KMT stays divided and open to Soviet influence;
In 194x, the Germans attack the USSR as per OTL, to make things simple, and the USSR does slightly worse/panicks more, leading them to leave China unsupported and without guarantees. The Japanese pick this moment, and the Americans back them for now.
By '54 some of China remains still unconquered (with Soviet support), Germany is no more, the US has rapproached with the USSR a tiny bit, and Japan's atrocious behaviour has become widely known. Embargo, attack on war-weary WAllies for oil and rubber, Pacific war in '54.
I don't know if I like this one, though. As i said, it's not easy.