If you do not have a second bator to put the first set into for the final 3 day to hatch I would only go with 1 set. I have put eggs that are a couple days apart in the hatcher at the same time but it is to hard to regulate for 2 very different hatch times. 1, you need to keep the humidity up for the hatch but that will be to high for the other growing eggs. 2, if you have to open the bator to turn the second set then you are letting valuable heat and humidity out for the hatching eggs. I hear you when you want to hatch a bunch but it is no good to rush them. I have 2 bators that for a while I used the one for many stages of eggs and then when one set would be ready to set for hatching I moved them to the second bator and was able to continue turning the others. With 2 you can always buy extra eggs and set them not worring about hatch dates. Just face it you need 2. Jenn