Here's a running (and incomplete) list of albums that I feel herald the coming of the breakout of the Jazz-Rock Fusion movement.
John Coltrane A Love Supreme (Jan. 1965)
Herbie Hancock Maiden Voyage (May 1965)
Miles Davis Quintet E.S.P. (Aug. 1965)
Anthony ("Tony") Williams Spring (Late 1965)
The Free Spirits Out of Sight and Sound (Jan-Feb 1967)
Miles Davis Quintet Miles Smiles (Feb. 1967)
Don Ellis Orchestra 'Live' at Monterey ! (March 1967)
Francis Vincent Zappa and the Abnuceals Emuukha Electric Symphony Orchestra Lumpy Gravy (Aug. 7, 1967: the 4-track StereoPak release from Columbia Records)
Don Ellis Orchestra Live in 3⅔/4 Time (Summer 1967)
Miles Davis Quintet Sorcerer (Oct. 1967)
Gary Burton Duster (Nov. 1967)
Don Ellis Orchestra Electric Bath (Dec. 1967)
Miles Davis Quintet Nefertiti (Jan. 1968)
Jeremy Steig Jeremy & The Satyrs (Jan-Feb 1968)
The Mothers of Invention We're Only in it for the Money (March 1968)
Herbie Hancock Speak Like a Child (March 1968)
Don Ellis Orchestra Shock Treatment (May 1968)
Francis Vincent Zappa and the Abnuceals Emuukha Electric Symphony Orchestra Lumpy Gravy (re-released by Verve Records in May 1968)
Miles Davis Quintet Miles in the Sky (July 1968)
Don Ellis Orchestra Autumn (Dec. 1968)
Nat Adderley Calling Out Loud (Jan. 1969)
Miles Davis Filles de Kilamanjaro (Feb. 1969)
Larry Coryell Lady Coryell (April 1969)
The Mothers of Invention Uncle Meat (April 21, 1969)
John McLaughlin Extrapolations (July 1969)
Miles Davis In a Silent Way (Aug. 1969)
Tony Williams Lifetime Emergency! (Aug. 1969)
Frank Zappa Hot Rats (Oct. 1969)
Larry Coryell Coryell (late 1969)
Donald Byrd Fancy Free (Dec. 1969)
Miles Davis Bitches Brew (Jan. 1970)
Herbie Mann Stone Flute (Jan. 1970)
Miroslav Vitous Infinite Search (March 1970)
Nucleus Elastic Rock (March 1970)
Freddie Hubbard Red Clay (May 1970)
Jean-Luc Ponty King Kong: Jean-Luc Ponty Plays the Music of Frank Zappa (May 1970)
Jeremy Steig Legwork (recorded Feb. 11, 1970)
Jeremy Steig Wayfaring Stranger (recorded Feb. 11, 1970)
John McLaughlin Devotion (Sept. 1970)
Donald Byrd Electric Byrd (Nov. 1970)
Larry Coryell Spaces (Nov. 1970)
Miroslav Vitous Purple (Dec. 1970)
Tony Williams Lifetime (Turn It Over) (Dec. 1970)
Association (Pierre Courbois) Earwax (recorded in August of 1970, released late in 1970)
Jeremy Steig Energy (I Giganti del Jazz, Vol. 15)
If you have any other albums from this period that you think might fit the description "Proto-Jazz-Rock Fusion" please make your suggestions in the comments section!