From which years in the future are the terminators in Terminator 1, 2 and 3 sent back?
Terminator 1: 2029 to 1984
Terminator 2: 2029 to 1994/95
There is slight confusion in year Terminator 2 takes place in, Per IMDB:
The first Terminator film takes place in May 1984. According to information provided at the beginning of the movie, it is now 1995, since John was born on 28 February 1985 and is currently 10 years old. If that's the case, it contradicts the T-800's claim that it was sent back 35 years in time (from 2029), which would place the film in 1994. Another contradiction is when The Terminator states "in three years Cyberdyne will..." which indicates the film takes place three years before Judgement Day (which occurs in 1997), again making it 1994.
Terminator 3: 2032 to 2004
Following is graphical representation from Terminator wiki