I have said for a long time the 4th of July would be the best time for her to announce. It may be that waiting to long after that would foster the perception, she is weak in her ability to make a decision. It may not be the reality, (I believe she has a strategy) but perception is a strong force.
I have heard that she must wait for two years after she resigned as Governor to run for another public office or else she would open herself to all kind of lawsuits from those troublemakers in Alaska.....just waiting for an opportunity.
Labor Day sounds great with me.