Here is my 100% Achievement Guide with Timestamps :)
Hope this helps :)
Intro - 0:00
Start - 1:30
Day 1 - 7:30
1. Good First Day & Day 2 Start - 19:00
2. Love Turts - 22:30
3. ShutterBug - 24:40
4. Back To Work & Day 3 Start - 33:30
Day 9 Start - 37:00
Day 15 Start - 38:10
Day 33 Start - 39:20
Day 64 Start - 42:05
Day 76 Start - 45:05
5. Someone's Out Here & Day 77 Start - 52:50
6. The Life & Times of Raccoon Carter - 55:55
7. Ol' Shoshone - 57:00
8. Bee Plot - 1:00:40
Day 77 Continued - 1:05:00
9. Burn The Place Down & Day 78 Start - 1:09:05
Day 79 Start - 1:19:30
10. Firewatch - 1:31:30