24 hours is no big deal. Just split the difference, and do you lockdown halfway through the day its scheduled for the first batch -- they'll go into lockdown 12 hours late (in theory), the others 12 hours early. No need to turn the last eggs after that point, either, it will be fine. Keep it closed as much as possible to keep the humidity up.
In practice, eggs will hatch over a 2-3 day period anyway, so don't be surprised if a couple of the first batch hatch after one or two of the second batch.
Now, if you get to the point where you've got eggs with more than a 24 hour spread, you should plan on getting a second incubator so you don't face these issues again. Then, you can use one for incubating and one for hatching.