Ways Skynet could've succeeded in T2

1) Send a T-1000 back 5 minutes before any of the events that happened after the T-800 located Sarah.

-Skynet knew she'd be in club Tech Noir so it could've sent the T-1000 there and it could've waited for her to show up. It could've killed her as soon as she walked up to the entrance.

-Skynet also knew she'd be at the police station. Again, the T-1000 could've went there and waited for her to show up. He took the identity of an officer so he shouldn't have had any problems doing so.

-At this point Skynet should've known where she worked since the other two Sarah's were eliminated. There would've been a complete paper trail for it to follow. The T-1000 could've acted like a customer until she showed up for her shift.

-And the most obvious place, the factory at the end. The T-1000 could've waited and killed her on the way in, or killed her on the way out.

2) Jon Connor had a juvenile record. Why didn't they send the T-1000 to the scene of his crimes and have it wait for him to show up?

3) Jon was in the foster care system. There would be a record of everywhere he had been since Sarah was arrested. Why not just visit him in one of those places and kill him? And while on this subject, the T-1000 shouldn't have had to use the police computer to find his address. Skynet should have already known what it was. Again, juvenile records.

There were plenty of other opportunities that Skynet could have taken advantage of. These are the main ones that immediately come to mind.

And I know that a few of them involve revisiting T1's timeframe, but Skynet has that capability. The lines, as far as moments in time are concerned, are erased.