People already shared so probably useless but here's the locations of all 8 collectibles as of 0.61 update :
Careful, collectibles only appears after you first meet Dilan in chap 2
- In Anna's Living room, under the table
- At work, where Diane's desk is, under a grey chair
- Downtown 1, next to the red car (Day)
- Upper Downtown, on the sidewalk a little to the right
- In the sex shop, once Emily invites you to go with her
- Industrial, under the motocycle (Night)
- Red light district, on the ground just below and left of the guy in yellow suit (Night)
- Shopping Street, near the knee of the woman walking with a guy. (Day)
Hope it'll help ; have fun guys.