The paper I recieved said I had roughly 6 weeks to send in my passport for the visa or pick it up in person. If I remember correctly, if you send it in it takes 3-4 weeks from the time they recieve it to issue the visa. The paper will have specific info on how to send it. The time you have to land depends on when your medical expires (The medical is good for one year). In my case it was Feb 22, 2011.
I recieved the PPR via email. Here are some links they included:
Passport Submission
http://www.canadainternational.gc.ca/buffalo/imm/submit_soumettre.aspx
Passport requirement:
http://www.canadainternational.gc.ca/buffalo/imm/passports_passeports.aspx
Photos, height, eye colour http://www.canadainternational.gc.ca/buffalo/imm/Photographs_Photographies.aspx
For family members:
http://www.canadainternational.gc.ca/buffalo/imm/notice_avis.aspx
I chose Seattle as my interview place, but Buffalo does all the visa stuff.