I would worry more about what would happen if they decided to pip while the humidity isn't up yet. Lockdown on day 23 has worked well for me, but there are a lot of variables in hatching.
You could always candle and watch for internal pips on Friday and then go with your gut feeling. If the air cells haven't dropped enough, then I'd consider waiting.
I like my humidity between 75-80%, but you've got to go with what works best for you.
My birds like to come early. If I try to wait until day 25, I'll end up with pippers in the turner... and once, hatchlings surfing on the turner. I set really fresh eggs, so I think that's a factor.
The first hatch is different, because the temps tend to run lower for the whole incubation cycle. Once I have heat lamps going in my hatch room, it changes the dynamic a bit.