Negative at 23 days is a good indicator however most would recommend getting tested at the 4-6 week mark and the 23rd day is just the beginning of the 4th. If it were me I'd wait til the end of the 6th for a definitive result. The Ora method is just as good as any.
It should be accurate up to around 80%.
If you would read the OraSure leaflet. It says, testing is 6 weeks- 13 weeks and maybe longer for the body to build up enough antibodies for their test to test reliably.