The RV for various ICBMs are still being worked on to reduce weight. The warheads themselves are pretty miniaturized already. While it is possible for China to continue miniaturizing them (eg using HEU temper instead of DU temper), it may not be worthwhile from a maintenance/logistics perspective.
Switching from no first use to first use only takes 1 minute. Make announcement and launch the missile 1 min after. Besides, in nuke war, what's the point to keep upright?
Well I guess China should end its no first use nuke policy if the US's Asian allies are okay with the US using nukes first on China. Also China if it has such a policy should stop its policy not to use nukes against non-nuclear countries if they're allied with the US.
Further proof that China's nuclear deterrence is woefully inadequate when former military officers are casually writing articles in military magazines about nuclear war without blowback. China needs to up its nukes in the thousands and shout from the roof tops about its numbers. You will never see anyone casually threatening nuclear war with Russia because it has adequate deterrence.