Those are reasonable routes although you could also use the JR Keihin-Tohoku local line if the time is more convenient. For this sort of thing, I'd probably use the HyperDia rail planner instead of Google.

http://www.hyperdia.com/en/

You will run into some commuter issues, particularly on the way to NRT in the morning. Leave plenty of time to get to Nippori. The Skyliner is rarely crowded any time.