Depends on portion of that station to be Interlocked. Time span for NI work at various big stations:
click hereBhusaval April 6-18, Arakkonam Jn April 5-14, Hoshangabad Jan31- Feb 11, Bengaluru Cantt Feb 9 -10, Saharsa Jan 30- Feb 5, Champa Jan 7- Feb 2, SoneNagar Jan 16- Jan 26, Manduadih Dec 27 2018-Jan 13 2019