This is a timeline of events that happened during the Fifth season or approximately June, 2011 to May, 2012
The Timeline
2011 Amy starts shaving her legs [the vacation solution]
88. “The Skank Reflex Analysis”
June 4, 2011 – Leonard has an analysis session with his mom
Saturday, June 6, 2011 – the boys play paintball –penny gets commercial
day 3 – watch commercial -much later
89. "The Infestation Hypothesis"
June 9, 2011 – Leonard’s dinfast with Priya
June 10, 2011 – Sheldon tries to get rid of Penny’s new chair
June 11, 2011 – Howard demonstrates cybersex devices, the chair thrown out
90. "The Pulled Groin Extrapolation"
June 16, 2011 – Amy stays & drafts Leonard to attend a wedding with her, Howard and Bernadette fight about where they’re going to live
Friday, June 17, 2011 – Leonard & Amy go to a wedding
Saturday, June 18, 2011 – Bernadette serves Howard breakfast
91. "The Wiggly Finger Catalyst"
June 23, 2011 – Howard & Bernadette register at Macy’s
June 24, 2011 – play D&D
June 25, 2011– Raj meets Emily
July 25, 2011 – learn Raj rich, Raj gives gifts to Emily
July 26, 2011 - Penny confront Emily
July 27, 2011 - Raj dumps Emily due to parents threat
July 28, 2011 – Raj seeks comfort from Penny
92. "The Russian Rocket Reaction"
October 6, 2011 – Howard going to space, invited to Wil Wheaton’s party
October 13, 2011 – discussion of Bernadette telling Howard’s mom about space
October 14, 2011 – Wil Wheaton’s party
93. "The Rhinitis Revelation"
October 20, 2011 – Mrs Cooper arrives
October 22, 2011 – Sheldon & mom do laundry
October 23, 2011 – tour Hollywood, Sheldon gets sick
94. "The Good Guy Fluctuation"
October 27, 2011 – Howard & Raj scare Sheldon
October 28, 2011 – Leonard meets Alice
October 29, 2011 – Leonard talks with Penny, ends it with Alice & Priya
95. "The Isolation Permutation"
November 3, 2011 – discussion of bridesmaid dresses
November 4, 2011 – Penny & Bernadette go shopping
November 5, 2011 – guys tell Penny & Bernadette that Amy upset
November 6, 2011 – Penny & Bernadette talk to Amy who gets drunk
November 7, 2011 – Benadette asks Amy to be maid of honor
November 8, 2011 – Penny, Amy & Bernadette go shopping
96. "The Ornithophobia Diffusion"
November 10, 2011 – Leonard & Penny go to movies, Sheldon terrorized by bird
97. “The Flaming Spitoon Acquisition”
November 17, 2011 – Stuart meets Amy
November 18, 2011 – Stuart texts Amy
November 19, 2011 – Stuart & Amy date
November 20, 2011 – boys play mystic warlords
November 21, 2011 – Sheldon asks Penny out, then asks Amy to be girlfriend
November 22, 2011 – girls play twister
98. "The Speckerman Recurrence"
December 10, 2011 – Leonard gets e-mail from Jimmy Speckerman
December 11, 2011 – Leonard meets Jimmy Speckerman, girls visit charity bin
December 12, 2011 – Jimmy Speckerman chases Sheldon & Leonard, girls return to bin
Jan, 2012 Penny dings a Mercedes, but doesn’t leave note [The Vacation Solution]
99. "The Shiny Trinket Maneuver"
Thursday, January 12, 2012 – Sheldon & Amy on date & gets upset
January 13, 2012 – Penny and Sheldon go jewelry shopping
100. “The Recombination Hypothesis”
January 19, 2012 – Leonard asks Penny out
101. “The Beta Test Initiation”
January 19, 2012 – Leonard & Penny’s date
January 20, 2012 – they watch Dr. Who
January 21, 2012 – Siri dinner & shooting range
102. "The Friendship Contraction"
February 2, 2012 – Leonard drives Sheldon to train store in Garden Grove
February 3, 2012 – they end roommate agreement
February 4, 2012 – power outage
February 5, 2012 – Howard talks to Mass
103. "The Vacation Solution"
Friday February 10, 2012 - Dr. Seibert tells Sheldon must take vacation
Monday, Feb. 13, 2012 - Sheldon tries to sneak in to work
February 14, 2012 – Sheldon at Amy’s lab
February 15, 2012 – Sheldon apologizes
February 16, 2012 –Howard & Bernadette discuss pre-nup
104. "The Rothman Disintegration”
February 16, 2012 – Prof Rothman’s retirement party
February 17, 2012 – Amy gives picture
February 18, 2012 – Sheldon & Kripke argue
February 19, 2012 – Sheldon & Kripke play basketball
February 20, 2012 – Sheldon moves in office
105. "The Werewolf Transformation"
February 23, 2012 – Sheldon doesn’t get haircut from Angelo
Monday, February 24, 2012 - Howard in Houston, Sheldon at hospital
February 25, 2012 – Howard returns from survival training
February 26, 2012 – Bernadette goes to Houston, mom already there, Penny cuts Sheldon’s hair
106. "The Weekend Vortex"
March 8, 2012 - games weekend proposed
March 9, 2012 – Sheldon shops at comic book store for present for Amy’s aunt Flora
Saturday, March 10, 2012 – 93rd b-day party Amy’s aunt flora, Amy makes scene
107. "The Transporter Malfunction”
March 29, 2012 – discuss Raj wants to get married
March 30, 2012 – meets Lakshmi
March 31, 2012 – date with Lakshmi, Sheldon breaks toy `
April 1, 2012 – Raj ends with Lakshmi, Sheldon confesses
108. “The Hawking Excitation"
April 5, 2012 – Howard says Hawking coming to Cal Tech
April 6, 2012 – talk about Hawking
April 7, 2012 – Sheldon cleans Howard’s belt buckles
April 8, 2012 – Sheldon dresses as French maid
April 8, 2012 – Sheldon shops with Mrs. Wolowitz
April 10, 2012 - meets Hawking, faints
109. “The Stag Convergence”
April 26, 2012 – discuss bachelor party
April 27, 2012 – bachelor party
110. "The Launch Acceleration"
May 3, 2012 – mission cancelled
May 10, 2012 – guys shop, Amy & Sheldon’s date. Leonard proposes
111. “The Countdown Reflection"
Friday – May 10, 2012 – Howard gives star necklace
Sunday May 12, 2012 – wedding of Howard & Bernadette
May 15, 2012 – Howard is launched into space
.
Notes
It is presumed that the first day of an episode is the date that episode was broadcast, but there are exceptions as in this season. 'The Wiggly Finger Catalyst' takes a month and would mess uip the rest of the timeline.if it happened on the broadcast date.