Last year from Miami, we boarded the Explorer at 11:00AM, and again in March, the Majesty of the Seas, about 11:15AM. I would assume the Voyager would be the same. We always come a day early now and stay in Miami near Bayside Marketplace. There is a lot to see and do there. Hope this helps out.
NCL Dawn (Repo 14 nite) 11-1-09
RCCL Mariner of the Sea (Mexican Riviera) 4-18-10
Are you using RCI transfer? If so I think once we got everyone on the bus we were there in 15-20 minutes. Weve boarded other ships around the same time too-11-12. I think it all depends on how long it takes them to unload the previous group and luggage, but by now theyve got it down to a science!