Well the first time that I did my hatch I really wrote down a lot of stuff and the numbers on my hygrometer.Very interesting. I kept it close to 30% up until day 18. Cool to know lockdown can be done at a lower humidity.
When eggs start externally pipping they release humidity into the incubator so even if I keep it at 30% after the 18 days, once I start getting external pips it will go up to 45% or 50% by itself.