Yeh I’m exactly the same when I hatch a new species. All I can say is waterfowl like humidity. So I would go by that pre use and do what I normally do and go for 70%.
But it’s very easy for me to say that when I’m not the one having to do it.
Please let us know what you do and how it goes, will...
Personally when I get pips my humidity gets upped to 70%, I like it to be very humid because I pull chicks out after they have hatched.
I also drop the temperature to 37.1c for lockdown and hatching, but that is my preference because I run so high hunidity.