Somehow you need to figure out how to reset your clock in your mind so that work starts 30 minutes earlier than reality. So if work starts at 8, you need to convince yourself it starts at 7:30. That gives you time to be late, plus built in time for traffic, parking, clocking in, getting coffee, etc. I’m not sure what this would look like for you, whether it would require you to set your watch fast, always plan to be there at 7:30, change your “leave time,” or what.
For example, I need to leave the house by 7:40 to be at work on time, but I have my “leave time” as 7:30, because if I leave the house at 7:40, I won’t actually leave the house until 7:40. Because I forgot my keys, sweater, wedding ring, lunch, kid’s bag, etc. Or because the toddler had a tantrum right as we walked out the door. If the toddler is ready to leave at 7:20, I get my things and we leave then, because if I delay, he stops being ready and we’re late.
I also set alarms. For example, I have an hour lunch, which is enough time to go home. But then I can’t relax because I know I’m going to be late. Or I do my math wrong, etc. So I set an alarm when I leave work that goes off with enough time to get back to work.