Got some interesting rumors:
It seems PLARF built at least 30 new DF-5 silos, making the number up to 48. It is not a news and everyone knew it or heard about it at least from 2020. But it took almost 4 years from construction to completion.
If the timescale also applies to solid ICBM silo fields, we wouldn't see the earliest silos completion until late 2024, in line with heavy ICBM development.
That being said, it is so weird that CASC tested solid ICBM engine back in late 2018 but YF-581 in the middle of 2021, which means solid ICBM development is much faster than the liquid one. But on the contrary, liquid silo field constructions are 3 years earlier than solid one, a mismatch between silos and ICBMs.
As reference, CASC tested engine for DF-41 around 2007 or 2008 and conducted first flight in 2012. The test fire of new solid ICBM could be imminent if it follows a similar pattern like DF-41. It could enter the initial phase of deployment in Yumen from 2024 and gradually ramp up production rate to fill other silo fields once they are completed.
I have circled out new factory expansion of CASC's solid engine factory since 2016, not surprising as the solid rocket department is poised to triple its revenue during the past decade.