Since your date does not include the year, no comma is necessary. Therefore, your sentence is punctuated correctly.

On June 6 at 4:00 p.m., I responded to the scene.

Thank you.

There is no hard and fast rule on this, especially for invitations. Invitations have their own sets of rules and styles and do not always follow the rules for formal writing.

We recommend using the preposition “at” instead of “on.”
“Submission time is at or before 3pm.”
To simplify, you could write “Submission is due by 3pm.”

As the post states, some writers spell out the time of day; others prefer numbers. This is a matter of style choice. Therefore, eight thirty or 8:30 is correct.

1. She arrived at 8:30.
2. She arrived at eight thirty.
3. She arrived at eight-thirty.

To ensure clarity, we would suggest writing it as either “1:00 p.m. to 7:00 p.m.” or “1:00 p.m.-7:00 p.m.”

Can I write it like this?
1 – 7:30 p.m.