You need to relax...the updates are rolled out based on IMEI or carrier or something similar which is why updates don't happen immediately for everyone. If all Nexus phones got the update at the same time, the servers would be overloaded for months.
As for update ability of your phone, don't worry about it - if it works normally, then it will update normally. Worst case scenario is you would have to do a Factory Reset to wipe it and then update it.
As I said, updates roll out according to an unknown schedule. I believe it has something to do with IMEI as well as carriers (and some secret algorithm). So if you don't get it right away, it's not an issue. I went through the same thing with my Nexus S, the updates didn't roll out for me very quick while others on the same carrier were getting it.
If the version you have now works fine, and it sounds like it does, just wait and the phone will notify you when an update is available.
In the mean time, have a beer and relax.