Just got back from our 5 PM reservations. We were directed to enter through the Tangaroa Terrace entrance to check in. The reservation/standby line was one and the same, so once we registered, we stood to the side until a waiter seated us. We were seated dot on time at the bar, inside, and as it was kinda warm this afternoon, that would have been our preference. This was a first time visit for us.
We ordered the Uh Oah, and the show that goes along with the serving was worth the visit, IMO. Good vibes in the place offset the so-so food. Service was not the best, but these days, no place is anymore, Disney or no.
We would go back for the atmosphere, but not the food. Can't answer your question about the 4 PM issue.