I have a hunch that it is very very likely that China will start a regional war in the next 5 years; S/E China sea, local trade routes, impacting Taiwan, Japan and maybe others.
All or nothing gamble, willing to go at it with the USA with the hope that if the Chinese MIL inflicts enough damage and hurt on the US Navy and AF (via suicidal 1way mission tactics), the USA will back down because of the cost, time and human resources necessary to replace lost ships, planes and personnel (most imp!).
Strategically the time to strike is anytime from now to 5-8 years out while USA replaces and updates all the electronic hardware thats been comped and ramps up American based naval and other defense industries.
Similar to Japan MIL thinking prior to Pearl Harbor. The Japs figured that if they wait any longer the USA Pacific Navy will just grow stronger and bigger and will be unstoppable. Strike early and hope that inflicts enough damage and pain to act as a deterrent.