Guangzhou Pearl River Cruise and want to know the schedule issue

We are very interested in the doing the Pearl River night cruise. We fly out at midnight so should have enough time. We were thinking the 6.45pm option (leaving from where?). Or are there a lot more options around 7.30? But would it be dark at the start? Are there taxis where the cruise finishes so we can go straight to the airport?
I asked these questions previously but could not retrieve the answer. Thank you