If you don't want fertilized eggs, you'll have to get rid of the rooster or house him apart from the hens.
A rooster will mate any hen when they're both of age. When rooster mates a hen, her eggs will be fertile for about 2 weeks.
That said.....you'll never be able to tell the difference. Folks the world round have eaten fertile eggs every day and no problems. I've personally kept roosters with my laying flocks for 20 years and except whenI was ill and not able to care for the birds myself, there have been no icky surprises.
Once a egg is fertile, it hangs out in a kind of stasis until it's incubated. You have to incubate an egg at about 100 degrees for 3 days to start to get blood vessel developmnet.
If you collect your eggs daily or even every other day, no development will start. You'll never get a partially developed chick in an egg.
But, as I said, if the thought is too, get rid of the rooster. No reason to keep him, really, if you're not going to be breeding. He's just taking up pen space you could use for another layer.
