Delaying the optional subject decision is one of the most structurally damaging mistakes a first-timer can make, because optional preparation must run in parallel with GS preparation from day one.

Timeline recommendation:

• Week 1 to 2: Shortlist 3 to 4 subjects based on interest and academic background
• Week 3 to 4: Do a 7-day pilot — read 80 to 100 pages of the standard book / syllabus for each finalist, and attempt 2 to 3 PYQ answers from each
• Month 2: Commit to one optional and begin structured preparation
• Month 3 onwards: Run optional preparation at 3 to 4 hours per week alongside GS

Selection criteria in order of importance:

1. Genuine interest — you will spend 500+ hours with this subject
2. Overlap with GS syllabus (reduces total preparation load)
3. Availability of good study material, coaching, and answer-writing feedback
4. Marking trends in recent years (check 5 years of Mains marks data)
5. Academic background (if you have a degree-level foundation in the subject, use it)

If your choice is wrong: Many coaches suggest the 3-month test — if after 3 months of sincere preparation you are still struggling to enjoy or retain the optional material, switching is preferable to continuing with a bad fit. Switching after Month 6 is almost always too late for that cycle.

Popular optionals with significant GS overlap: Geography, Political Science and International Relations (PSIR), History, Sociology, Public Administration. Shakti Dubey (CSE 2024 AIR 1) chose PSIR explicitly for its GS overlap alongside her interest in the subject.