Question : How long do most people stay in Oslo when they fly in from Mumbai?
Answer : Of course you're not most people, but if you were, you'd stay roughly 10 days.
Question : Is price more important than specific travel days for you?
Answer : In February, Tuesday is your cheapest day to fly. Flexibility is paramount when booking travel plans in order to keep costs down.
Question : How often are prices changing for this route?
Answer : Flight prices for BOM to OSL change a lot more than the majority of routes. However, the sooner you book, the better price you tend to get.