First Rooster normally have to be between 4-6 months old before they start fertilizing eggs and it can take even longer depending on breed.
Second you can check your fertility before spending so much time or effort to find out.
Crack an egg open, look for a white bullseye that is a fertile egg. Otherwise not fertile not going to make a chick no matter what. There are threads with pictures if you want to see some and more description search for that.
Third, The natural way is a hen that sits on them. Do you have a broody hen, one that stays on the nest and won't leave? She has to sit on those eggs for 21 days only breaking for food, water, and poop breaks.
The natural way works great but remember nature doesn't just spit out babies 24/7 all year round. Make sure you have all the components for the natural way.
Otherwise you can incubate but you still want to check your fertility rate or you will still get rotten eggs.
Good Luck.