Filming dates are my best guesses unless otherwise noted.
Sources: Spoiler TV, andreas_ri, & dean_sam.
7x01 - "Meet The New Boss" (Filmed from July 18th [confirmed] to July 27th) Spoilery Pics
7x02 - "Hello Cruel World" (Filmed from July 28th [confirmed] to Aug 9th)
7x03 - "The Girl Next Door" Directed by Jensen Ackles (Filmed from July 6th [confirmed] to July 15th [confirmed])
7x04 - "Defending Your Life" (Filmed from August 10th to August 19th)
7x05 - "Shut Up, Dr. Phil" (Filmed from August 22nd to August 31st)
7x06 - "Slash Fiction" (Filmed from Sept 1st to Sept 13th)
7x08 - "Season Seven, Time for a Wedding!" (Filmed from Sept 26th [confirmed*] to Oct 5th)
7x09 - "How To Win Friends And Influence Monsters" (Filmed from Oct 6th [confirmed by dir.] to Oct 18th)
7x11 - "Adventures In Babysitting" (Filmed from Oct 28th to Nov 8th)
7x14 - "Plucky Pennywhistle's Magic Menagerie" (Filmed from Dec 7th to Dec 16th [confirmed ^])
7x15 - "Repo Man" (Filmed from Jan 4th to Jan 13th)
7x17 - "The Born-Again Identity” (Filmed from Jan 26th to Feb 6th)
7x18 - “Party On, Garth” (Filmed from Feb 7th to Feb 17th)
7x19 - “Of Grave Importance” (Filmed from Feb 20th to Mar 2nd) ++
7x20 - "The Girl With The Dungeons And Dragons Tattoo" (Filmed from Mar 5th^^ to Mar 14th)
7x21 - "In Case Of Emergency" "Reading Is Fundamental" (Filmed from Mar 15th to Mar 26th)
7x22 - "There Will Be Blood" (Filmed from Mar 27th to April 5th)
7x23 - "Get Dick" "Survival Of The Fittest" (Filmed from April 6th to April 19th)
According to @taralarsen the crew didn't wrap until 4 in the morning on April 20th.)
* These 2 dates were confirmed by a fan on location, talking to the crew on Sept. 21st.
** Jared Tweeted that he was leaving for home on Friday (Nov 18th) evening and wouldn't be back up to Vancouver until Nov. 28th, meaning the production has the whole Thanksgiving week off.
^ Producer, Jim Michaels tweeted about leaving Vancouver for Chicago - HERE and Location Manager, Russ Hamilton tweeted about leaving the studio and not returning until Jan. 3rd, 2012 - HERE.
++ Word has it Jensen & Jared had Thurs & Fri off (Feb. 23rd & 24th). Source in comments
^^ Confirmed by Jensen & Jared on March 4th, 2012, at Burbank Con.
If anyone has further info. to share about anything here, I'm always happy to receive it. :)