THis is a matter of opinion.Those little red caps that close the holes ..do ya leave both out or one in til day 18 than remove both? Thanks
Both must be out by day 18-- that is a given.
As I have a fan in my LG and that move more air thru the incubator, I do play with which hole I plug to fine tune the temp without touching the thermostat knob. Covering the fan hole holds in more heat than if the other hole without a fan is covered. SO fine turning of the temps.
Realize that these are growing babies that depend on sufficient air flow to get the oxygen that they need to live and grow.
Some people leave out the plugs always; this can be done if another incubator is used for the last 3 days of hatching.
Hopefully you will hear some other opinions as well as others chime in.