Hey, Sharon.
If his head is continuing to grow at a rapid rate, and his ventricles are enlarging, there is no reason to wait on surgery. It will just prolong the inevitable and lead to brain damage (which he may already have, given that he's not verbal). Any child who is showing delays
and evidence of CSF pressure and ventricle enlargement will need surgery, and putting it off will only decrease any chance of catching him up.
Good luck...
LIZARD