The first day I would build
Give the city one clear route before adding extras.
- Start with Marina Beach and Kapaleeshwarar Temple while energy is high.
- Use Fort St. George as the natural reset instead of crossing town too early.
the easier plan is Kapaleeshwarar Temple or Government Museum first, food and shopping in the middle, Marina Beach near sunset. That keeps the day readable instead of turning every good name into a separate detour.
I would rather leave one place for tomorrow than drag a tired route through San Thome Basilica just because it looked close on a map.