Got a taxi from Waikiki, $35 and 30 min trip, arrived about 8.30am, would recommend arriving earlier as it is hot even at 8.30 in the morning. Trail opens at 6am I think, a better time to start anyway. We are in our 50's, almost 60, and not fit but doing pretty good for our age. That said, this is not an easy trail and if we went again I would do some training beforehand. The railway sleepers are not like stairs, they are all over the shop, high, low, far apart, missing, rotting and very steep, especially at the top. We made it to the top in just under an hour, taking it easy with many short breaks. There were many people on the trail at this hour, all ages and fitness levels and all seemed to be doing it bit by bit with lots of rests, totally the way to go. The view from the top is amazing and so worth the effort. In some ways the decent is almost worse than the climb, fighting to keep balance with the steep decent, but much quicker going down.
My advice....
Do some fitness training beforehand
Go early to avoid the heat
Drink plenty of water
Take it at an easy pace with lots of rests - enjoy the view on the way up
Be mindful of others on the trail that are fitter or less fit than yourself
Just do it, you wont regret the view from the top, so worth it