Any person can file. You don't need to own a registered trademark. You can oppose if you believe the mark is similar to yours, likely to deceive consumers, filed in bad faith, or lacks distinctiveness.
Exactly 4 months from date of publication in the Trade Marks Journal. This is strict — no extension permitted. Missing it means losing the right to oppose that application.
Govt fee for TM-O form: ₹2,700/class. Our professional charges for filing start from ₹5,999 (includes drafting, evidence, hearing representation). Defense counter-statement: from ₹4,999.