For flights in North America I have found it to be less to book 2 one way flights than a return, and it allows you to mix carriers if one has a better time or price. If you see a price in your range for March 9 I would book it now .
Yes, for the best price you have to book as soon as they are released! I booked our flight there already, will book our return flight when it's available, I check the Westjet site daily...
WestJet is only available up until March 12th ... so I can't even book them yet ... My TA called them to find out why they are delayed in releasing flights ..they think it is because of the new low cost airline they are starting up .... they are 40 days late with flights ... Ohh you booked just going there .. shoot .. I really should have done that