My tickets have a 4pm time on them. Is that the time we can enter or it is the latest that we can arrive?

They're flexible. We showed up an hr early for our time and it was fine. I think it's just a way to try and losely control the flow of people.

Again agree with Paul. We showed up 20 mins early to ours and got in.

I also agree, however if that is the last entry for that day it is best that you arrive at that time.

I agree with Paul