Hirani's debut film "Munnabhai MBBS" was released on December 19, 2003, while his last two blockbusters, 2009 comedy "3 Idiots" and last year's "PK" were released on December 25 and December 19, respectively.
When asked if the biopic will follow the suit and release during Christmas, Hirani told PTI, "We will begin shooting mid next year, roughly around June. So yeah, (the film will release) roughly around that time only. It will take that much time, one-one and a half years, so yes."
The biopic stars actor Ranbir Kapoor in the titular role and will touch upon every aspect of Dutt's life - from the age of 17 till present.
The 53-year-old filmmaker says he has finished the first draft of the movie and is "waiting to progress" with it.
Ranbir will beef up to essay the role of Dutt but Hirani says they have not decided just how much weight the "Tamasha" actor will gain.
"We haven't started work in terms of all that. We are right now at the scripting stage. Once we get into production then all those details will come in."
Dutt, 56, is lodged at the Yerwada prison in Pune where he is serving the five-year sentence for possession of illegal arms and ammunition in connection with the 1993 Mumbai serial blasts case.
