You should be good to wade below the dam at minimum flow which is 7mw. Anything higher will be tough wading and dangerous this time of year. They usually blow the horn when they start generating during daylight hours, but they don't always blow when they bump the generation up a bit. I've never fished anywhere on the White or Norfork at night so I can't say what happens when they decide to increase generation.
Here is a link to Steve Dally's website that shows the estimated water rise times for various access points on the White. From what I have seen the fallout times are considerably slower.
https://ozarkflyfisherjournal.wordpress.com/2017/07/12/dallys-fly-fishing-report-71217/
Hope this helps and be careful.