Yes, they changed how they commissioned.
Before, shipyard did trials. If approved, ship goes to naval base and gets commissioned. Navy takes complete responsibility and ownership of the ship therein, trains the crew and so on, enters break in phase.
Now, shipyard does first set of basic trials using shipyard personnel. Then ship goes to its intended naval base for trials done under the Chinese Navy personnel, which at the same time, the Chinese Navy is honing the personnel for this ship. When Navy is satisfied --- and at times the ship still has to go back to the shipyard for fixes --- then the ship is finally commissioned at the naval base, complete with crew already trained for the ship. In this revised commissioning scheme, the ship now spends many months on the naval base doing trials and training with its crew and on the base it serves with before it gets its actual commission.
This change can be marked at the end of the first batch of 052D and at the beginning of the second batch, like 155 Nanjing and 120 Chengdu. Good example now is that 162 Nanning is going to get is formal commissioning soon, and yet she was already in Zhanjiang base doing second phase trials since late last year.
I should not try to compare this with the way the USN "commissions" its ships now. For example, the Zumwalt is "commissioned" for its power plant and its power train, but its weapon systems aren't.
