Should I start preparing for competitive exams alongside college?

I'm about to start college and I'm thinking of preparing for competitive/government exams alongside my bachelor's degree.

Do you think it's a good decision to start this early? If yes, how should a complete beginner start? I'm confused about where to begin, what subjects to focus on first, and which resources are actually useful.

I'd love to hear from people who prepared during college. What worked for you, and what would you do differently if you were starting again?

Thanks! 🙏