If we are to go by the typical PLAN practice, they'd have first try it out on smaller ships to have a feel for it before introducing it to something as major surface combatants as the 055.
Not really -- an "enclosed bow" isn't even some sort of high technology subsystem like a VLS, phased array radar or missile system that needs to be fielded in a limited way to be verified.
More importantly, the Chinese shipbuilding industry has now reached a stage where "typical" or "historical" Chinese naval shipbuilding practice of iterating new designs in small pairs before mass production, or testing subsystems in a limited way for a prolonged period, is no longer mass applicable for every type of ship anymore, and blanket assuming every new design feature or subsystem may need to be "tested out" before being deployed in a production vessel is now overly simplistic.
Increasingly, we will have to consider each new design feature or subsystem that may or may not be implemented in the context of the Chinese shipbuilding industry and the capability of the relevant supplier chain all in the present, and consider those features and subsystems within the context of the type of ship they're fielded on as well, instead of simply assuming anything new, large or small, should be expected to be tested on small scale first.
In the case of an "enclosed/low profile bow," I do think such a configuration is easily within the capabilities of the Chinese shipbuilding industry and design institutes, and is not something they would have to test on any sort of practical real world ship, before implementing on a production vessel, and can instead reach a sufficient degree of maturity and reassurance via their own internal R&D process.