The type 052D seems to be going through a quicker outfitting phase than the 052C's.................i did read a story that their were some teething problems with the improved engines fitted to the latest batch of 052C's hence the long time to entering service...
and i believe the 052D's use the same engines as the improved 052C class, so those problems would of been resolved before the fitting of these engines to the 052D.
But, as the 052D is a new toy for the Chinese navy it appears they are very keen to get them into service a.s.a.p...............the 052C's they are happy with, but it appeared the Chinese navy were not in a hurry to put them into service, in fact 150 and 151 hung around the fleet after completion for quite sometime before they were commissioned.
Anyway the last 2 052C's will go into service this year, with perhaps the first 052D................and the 4th should be launched very soon, and with the other 052D's at 'JN' and 'Dalian'...........then 2014 is the year of the Destroyer for the Chinese Navy.
Then next year (hopefully) China starts work on its '055' Destroyer/Cruiser.................which should be a real monster!