We went at 10:00AM on a Sunday and the queues were reasonable. We got through the queue and to the summit in around 15 mins. We booked 48 hours before and were able to get tickets. My 5-year old was free.
It wasn’t overly crowded but you’ll always have to wait for a corner shot or a space on the glass floor. I’d highly recommend this activity, however I didn’t give it 5 stars as the glass floor was disappointing as the view down isn’t great, you can’t see to ground level, maybe my expectations were wrong.