Upvote:2
I recently found a website showing reports that are interesting from this point of view.
Hopper shows much information in reports for any pair of origin/destination airports.
For you, I took the example of Montreal-Mumbai (as you did not specify which airports you targeted - I let you read the report for your expected trip). What we can see is it is cheaper in April - but March seems good as well. Apparently it is better to fly out on a Sunday and fly back on a Tuesday.
You can find more information in their full report but that might be too much and anyway it depends on a lot of things, including as @pnuts suggested, on the price of oil which varies a lot.