No point sending a high-value asset with a 750 km missile system into the dragon’s lair; that will be the last ditch solution. When the longer range K-4 missiles are inducted, the Arihant and its follow-ons will be stationed in the Bay of Bengal and Indian Ocean.
Doesn’t have to go into the Dragons lair. China can’t track a nuke in the Pacific and won’t be able to for some time.
They probably can’t track a sub 500+ km from their coast either.
A short fast run into firing range of coastal targets should be pretty safe.
The actual patrol zone could be out in the Pacific 2000+ miles from China.