If you calculated for 5ppm then it should be 5ppm and people have been cycling successfully with this concentration for years, but it is pushing the limits of how high your ammonia and nitrite can safely go so there is little room for error and that's why it's not recommended anymore. It's up to you whether you want to restart with the new cycling guide or stick with the 5ppm.
If you decide to do a water change then do 40%.
If you decide to do a water change then do 40%.
