When Does the Film "Hulk" (2003) Take Place?
"Hulk" is an adventure horror (kaiju) superhero film written by Michael France with John Turman, James Schamus, and David Hayter [adapting "The Incredible Hulk" #1 (1962) by Stan Lee as well as "The Incredible Hulk" #377 (1990) by Peter David] and released June 20th, 2003.
We know this because, roughly a quarter into the film, David Banner (based on the comic-book character Brian Banner) says, "The experiments, the accident. All top-secret. They put me away for 30 years." referring to the time he has been separated from his son Bruce. (Though, he certainly could be exaggerating or rounding down.) Through clues in the first prologue, this can be dated to 1972 AD.
1972 + 30 = 2002.
It takes place on an alternate timeline of the fictional Marvel Cinematic Universe in the year:
2002 AD
We know this because, roughly a quarter into the film, David Banner (based on the comic-book character Brian Banner) says, "The experiments, the accident. All top-secret. They put me away for 30 years." referring to the time he has been separated from his son Bruce. (Though, he certainly could be exaggerating or rounding down.) Through clues in the first prologue, this can be dated to 1972 AD.
1972 + 30 = 2002.
There are two prologues (and many dream-like flashbacks back to the first). The first begins with a montage of scientific genetic work that includes close-ups of various hand-written notes dated "8 FEB 1965" through "19 APRIL 1965". Then, one with "18 JUNE 1965" on it blows past the viewer. So this prologue opens in 1965 AD.
Soon after, a time and place setting title card appears over the footage that reads, "DESERT BASE 1966". Therefore, we absolutely pass through 1966 AD. Three shots later, there's another hand-written document that tells us we have moved on to "25 JUNE 1967". The next scene reveals that Edith Banner is pregnant in or after June of 1967 AD. Assuming about a 9-month pregnancy term, Bruce Banner is born in the next scene in 1968 AD. [In the following film, "The Incredible Hulk" (2008), according to his Culver University ID badge, Bruce Banner's birthdate appears to be December 18th, 1969 AD. "The Incredible Hulk" (2008) is meant to only loosely connect to this film.]
We then see some kind of intense exchange between Edith and David that young Bruce witnesses. Much later, General Thaddeus 'Thunderbolt' Ross says to Bruce Banner, "You were 4 years old when you saw it!" referring to this event. That roughly places this day in 1972 AD.
1968 + 4 = 1972.
Because of Bruce's age and the condition of his new toys later in 1972 AD, the Christmas morning depicted before this must be December of 1971 AD.
This is all immediately followed by a second two-part prologue in which the teenage Bruce experiences night terrors and then packing to leave for college for the first time, but (other than taking place in the mid-1980s AD) these both appear to be impossible to date.
Finally, there's a 2003 AD epilogue that's clearly labeled with a title card that says, "ONE YEAR LATER..."
2002 + 1 = 2003.
It was retroactively absorbed into the Marvel Cinematic Universe at a chronologically early place (a first chronological film to feature Bruce Banner/The Hulk) and can be watched either at its timeline point or entirely separately.