Day one temp spike question

I have the new RCOM max 20 incubator. I just had to get a new one as my old one from 2007 wouldn't regulate humidity so the manufacturers sold me a newer model since they no longer carried the parts...anyway. I brought the incubator to my sons class to let the class hatch the eggs (4th grade). I initially set the temp and humidity on the machine and watched it for an hour. The machine it self was reading much lower than my little gauge I had put in. I had the teacher watch the temp and humidity all day and when it had stabilized to 99.5 on the external gauge I bought, I told her she could put the eggs in (3:30 pm)

The temp had been staying at 99.5-was higher on the actual incubator digital read out, but I went with my gauge and it was more accurate at the time. Fast forward to this morning I texted her to see the readings and she said both gauges were reading identical but high at 100.5 and 100.4. I told her to lower the temps down to 99.5 and it went down within 5 minutes and its been stable since. Should I worry?

And the humidity gauges are reading slightly different (incubator says 60% and external one says 51%) not sure where I should aim for. Any thoughts and tips would be great.

If we stuck them in at 3:30 pm on April 4 when should I turn off the turner and expect them to hatch?

Thanks,
sorry its been about 7 years since I hatched any eggs I am rusty.

 

Thanks! That gal I bought my eggs at said 60 it's been so long I had the teacher reduce it to 50 for now