Looks like you have a good plan. FYI: There are two routes that go to the base of MT Whitney from the portal and share the first mile or so - the main trail, which you will be hiking, and the Mountaineers route (MR). The latter is more rugged and requires non-trivial alpine skills (it is rated class III). You don't need to worry about taking the wrong path since the turnout to MR is barely noticeable from the main trail.
