An accurate explanation of the complete timeline for T1, T2, T3, Terminator Salvation and Terminator Genisys.

T1 - 2029 to 1984 (J.D. 29th August 1997)
T2 - 2030 to 1995 (J.D. 25th July 2004)
T3 - 2033 to 2004 (J.D. 25th July 2004)
T4 - 2018
T5 - Skynet went back to 1995, waits until 2029
T5 - 2029 to 1973, 1984, 2014 (J.D. October 2017)