I can't give a definite answer as to what happens all the time, only give my experience.... JetBlue sent me a TrueBlue update telling me that the schedule would be extended on such and such a date at 12 noon. We went online to book our flight right away at 12 noon after we saw the rates were fantastic. The next day I got another (non TrueBlue specific) email alerting all email subscribers to JetBlue's extended schedule. For fun and comparison's sake, I checked our flight and it was already over $100 more.
As far as I can tell, TrueBlue members have advanced notice, and with that perhaps better flight prices, tho I will never understand the extraordinary price jumps and drops in airfare!! For all I know I could go online right now and book my same flight at the very low price I got. They fluctuate like crazy it seems!
So no, I couldn't book earlier than others, just had advanced notice!
Hope this helps! Good luck with your flights!!!