Welcome mwoyno55,
According to your post, the 'Time to Leave' alerts aren't working in the Apple Calendar app on your iPhone.
Create and edit events in Calendar on iPhone - Apple Support -- Are you adding the address to the location you’re traveling to under the event name? If you’re not, see if adding it provides the result you’re trying for.
If it still isn’t working, or you’re adding the address, we'd like to ask a few questions to better understand what's going on.
To start, have you noticed this with all Calendar events or just specific ones? Are you sharing these events with someone else? If possible, try to narrow down the issue. For example, does this occur with iCloud Calendar events?
Also, to confirm, you have the following enabled:
Settings > Privacy > Location Services > Calendar enabled 'While using the app'? Is Precise Location enabled?
Let us know and we'll take it from there, take care.