As suggested before, look up the cost to travel in the next few days (i.e. find the cost of flights reserved only a day or two in advance (but they'll be higher than they would be in October), then look at the cost for flights reserved well in advance, and find out the fee to make a change later. Compare the fare difference with the cost of making a change. You might decide it is worth booking now on your best-guess date and run the risk of paying the change fee in addition to the fare difference.
If you wait to book, you are guaranteed to pay the higher fare. If you book now, you will be better off if your timing is right, but you risk paying the change fee in addition to the higher fare, if your timing is off.
This is a dilemma I've had, too. It is risk management and there is no right answer. The airlines are doing exactly the same thing in their pricing - trying to determine how their customers will respond to price differences.
As an aside, I never complain about air fares being too high. They are SOOO cheap (relative to incomes, etc.) compared to my youth. However, I still do try to get the cheapest fare possible!
- Clare