If I buy nifty 10000 CE before almost 20 days of expire at the of spot price 9300
Afterthat nifty goes down, so premium also goes down. Theta alwayes reduce my premium. I think IV also against me.
After 10 days of such condition my premium becomes very low then a upmove comes IV also increase and my strike price becomes ITM or close to ITM.
In this situation will I get profit?
At this situation , chances of , even the ,break even or profitable position is 50:50 only.
If it expires ATM or just ITM maybe you will hardly break even, for your option to turn profitable in that situation it has to expire deep ITM.
Yes, if it becomes ITM you will get profit.
IV has inverse relationship with price move.
Use Option calculator for computation of theoretical values of your assumptions 