Pay attention to your tour guide and what they recommend. Our guide Patrick told us that after we got done at Ellis Island to come back to the 9/11 museum and the line would be down significantly. There were only 2 people ahead of us in line and we got our tickets at 5 minutes to 5:00 and walked right into the 5:00 tour. Out total time in line and in the door was less than 5 minutes.
Great tour and well worth the price .if you visit New York don't miss.
Our tour guide Patrick was very informative and entertaining - would highly recommend trip.