How many silkie eggs can a silkie incubate at one time?

its pretty straight forward, i have silkies, they start laying at about 5 months old and can cover about 12 to 15 eggs, a tip is keep taking the eggs off her and store them in a bucket of oats as it keeps them fresh, save up about 7 or 8 and then stop taking them off her and let her build up some eggs in the nest because she might just start hatching about 6 eggs and if she does then you have the previous 7 eggs you saved up, so thats 13 eggs under her if you know what i mean.