Check the employee handbook for details and definitions to see how they view PTO, etc. When I was originally hired they said my salary was calculated based on a 45-hour work week. While I usually fall an hour short, I do tend to work through my lunches (eat at my desk as I catch up on email or other lighter work) and there are a couple late nights or weekend events each year that balance that out.

Now: if I work a weekend event, I am told to take the equivalent time off elsewhere. That's fair, and it's nice to have the time back. If I have a dentist appointment or something, I can just go and come back. If I have to do an errand while shops are open, I can do that. As long as my work gets done it's all good.

For day to day, I tend to show up & leave at the same time. They like that since it's predictable for them. I'm usually a few minutes early and go home when I reach a stopping point. I found a vintage talking clock from the late 80s that still works and have it on my desk. I originally got it to annoy my office-mate but she thinks it's funny and it actually reminds us to head home on time. Setting a recurring alarm to remind you it's quitting time might help.

Overall I find salaried work more laid back, and setting your own routine helps keep a little structure for peace of mind. Just communicate to your supervisor about your comings & goings so they know how to plan.