The Afterwork Navigation League event at Houghton Valley in Wellington is one of a series of 3 hour rogaines in the evenings. These were initially designed as practice for longer events, but are perfectly good as ends in themselves.
This event was originally scheduled for November 15th but was postponed to November 22nd due to the earthquakes & flooding.
These events are usually 3 hours, but occasionally might be shorter. Maps are available from 5:20pm, briefing 5:50pm, and rogaine from 6pm to 9pm. For locations further out these might be half an hour later. If you can't get there by then why worry - just rogaine for a shorter time. In fact if you want a shorter period tell the organiser and just do it!