It's not so much whether he dials 999, it's the notion that he instinctively would go for the phone. Probably if he did reach the phone and dial, he'd suddenly find he couldn't speak due to his injuries.
The time-and-motion thing is your assumption: I've outlined my issue with it above. I can't reconcile how Jeremy catches up with him in the kitchen. You claim Jeremy is only a few feet behind him, which to me leaves us with a paradox.
And actually, the theory of Nevill going for the phone is not new: I got the idea from people who think he is guilty.