Hi Maz, I didn't realize there was a set time as I have already been incubating for a month, the only problem I am facing right now is the freezing weather which has dropped humidity to 37%, much lower than I am used to in the UK. Next week things should warm back up again but I have another batch ready to hatch just before then and I am already struggling to maintain humidity. I might have to add some steaming buckets of water to the incubating room once I need to up humidity in final days but in the UK there is a strict chicken quarantine in place at the moment and they just discovered a new outbreak today so the lockdown for chickens will most likely be extended again end of the month.
Chicks should be kept indoors for the first month or two anyway by which time the weather will be good enough for them to go outdoors (even if it probably will have to be completely covered to prevent any wild birds getting near the chickens to the avian flu)