Well the ceremony is outdoors at 4:00pm but I don't see any indication in the OP as to where, what and when the reception is. Perhaps I missed it. That would be what sets my standard. I don't think that a ceremony happening before 5:00pm is really the standard of formality. I'm pretty sure that the only time I've ever in my life been to a ceremony after 5:00pm it was an outdoor wedding.
Really? I go to many. My daughter's wedding was at 6:30; mine was 6 or 6:30; I don't remember exactly.
I think different communities and religions may make a difference here. I believe in some churches ceremonies have or at one time had to be in the morning or anyway during the day, so some people still have the reception several hours later. It seems several ehellions who live in the UK report that that is common; do I have that
Jewish weddings can't be on Friday evenings, or on Saturdays until about an hour after sunset. So if you want a weekend evening wedding, you have to do a winter Saturday after dark or else Sunday of a three-day weekend -- which is why those are so popular for Jewish weddings. Mine was Sunday July 4, both my children did Labor Day weekend, and my sister-in-law and niece both did Memorial Day weekends.
So I guess that's one reason why different communities are used to daytime or evening weddings.