I don't know if he wore a watch; no one's ever mentioned it. Clocks in vehicles are notoriously wrong.
Phones are auto-synched, as are computers. If the security system was linked to a computer, the time should be pretty accurate. (IMO, someone as careful as Mr Security to have at least 7 security cameras, has the time synched pretty accurately.)
What makes sense to me, is that Steven sat in his car and checked his voicemails or even made a call, before he got out and started walking.
We really don't know. Really.
Clocks in cars are notoriously off. But many phones are not auto-synched. I had a regular phone through t-mobile and a Blackberry through AT&T. They were always a few minutes off. In fact, even when I tried to synch the Blackberry with the T-mobile, the Blackberry would eventually switch back. In fact, it wouldn't even change time zones when I would go back east.
As for computers, my Mac is five minutes ahead of Dell Laptop. And I don't think either of them is right on World Clock time.
All I am saying is that we have to give those camera clocks a bit of leeway. Probably a minute either way. And we still have no idea if Steven's clocks were on time or not. I think there is a bit more leeway in the "down to the second" timeframe than we think. We should not automatically think that because it is 30 seconds past noon on the clocks that he was going to be a minute late for whomever he was meeting. IF he was meeting someone, that is.
And we should not gauge the importance of that hypothetical meeting on the basis of two camera clocks that show him being a bit behind if he was headed to a noon meeting of some type on Evening Lights.