I think it’s reasonable to believe that Tim left the CDC campus and got home before he disappeared, based on where his belongings were when his parents arrived.
The parking lots and decks at CDC are pretty busy and even if the cameras didn’t pick up any footage of Tim getting in his vehicle and driving off, someone else would have seen something suspicious. After all, he left campus that Monday at a time when people were still arriving to work (people start at all different times at CDC- it seems like Tim started earlier than most, maybe to beat the traffic).
Edit: I almost always notice whenever I come into the garage in the morning and someone is already leaving. Mostly because I want to try and take their spot.
I think it's reasonable to conclude Tim left the parking lot and that he arrived home but there isn't any proof that we've been given. It was nice to read your explanation. Thank you.