Not that I'm an expert or anything here is my
When to change gears depends a lot on what type of riding that you are doing. If you are at the track and the intention is to go faster then gear changes are at peak or close to the peak horse power for that gear, which may or may not be at the rev limiter. The was a technical article in Sport Rider last year sometime about that.
One thing to consider in gear selection, which is directly related to speed and rpm, is the one that you choose to go through a turn on so that the bike is not chugging along. If it is too high of a gear and you are letting off on the gas during the turn to slow down you will be lightening the front end and you may lose it.
If it is too low the opposite is true as well. You want a gear that you can start the turn with the gas on and continue to roll on the gas throughout the turn. For smoothness you will not want to hit the rev limiter during the turn either, which would introduce the same above mentioned senario (sp). Changing gears during the turn may do the same.
For just riding around town just go with what feels comfortable and doesn't chug the engine and you should be in a postion to manuver in and out of situations as they come up. If you are chugging the engine then when you need to accelerate quickly it may take a while for the engine to catch up on the rpms.
Remember there ain't no trophy for getting somewhere quicker and you can only lose. Take your time to get comfortable and be smooth.
Hope this helps and enjoy the bike when you get it.