I would suggest putting the actual time, if you put 5:00 - you dont want your guests to arrive earlier than 5, thus having a 45 min or so wait for the wedding.
If you put 5:30 - you can word it as:
at half past five in the afternoon
or
at half past five o’clock in the afternoon
For Time not on the hour . . .
5:15 pm at a quarter past five o'clock in the afternoon
5:30 pm at half past five o'clock in the afternoon
5:45 pm at a quarter of six o'clock in the afternoon
Sincerely,
Krista
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