Multi trip to Canada/USA in November - HELP!

[wingnut1]

Help! I'm after some advice, as I've been a bit of a twit.  I planned to travel to Vancouver on 12th November and then onto a friend's in Cincinnati a few days later, then fly home. The prices are spiralling up, and I keep reading that if you wait til the last minute, I might get a good deal (I was planning to book a flight from Cincinnati to London now, then travel at some point to Vancouver within the 2 weeks I was there, and book the late deal for this trip before I leave the UK).  Does anyone out there have any experience of this/think its a good idea, or should I stop being tight and book the whole multistop trip now for the full price (�636 just for the flight - eek!) Thanks