We got to the border crossing at 0730 and there was already a small line. The border opens at 8 and we were on the bus to Petra around 0845.
It took about 30mins to cross back as there was really no line and I was back at the hotel around 730 that night. I think they tell you the average time to be back at the Israel border is 7pm.
It was a long day, but a great memory!