As stated, you cannot "make" a hen go broody. It is a hormone thingy, and even with a breed that DOES still have the broody instinct, it will not happen until a hen has layed a :"clutch". This may be as few 15 eggs or 40 or 50!. So do not leave eggs in the nest box. Eat and enjoy and refrigerate and eat the beautiful eggs!
Leaving an egg in the next can show hens WHERE to lay. If you have a number of hens, most will lay in just one or several nest boxes, maybe leaving others empty. Why? Wouldn't you like to crawl into a warm bed, safe place? So do hens! And do you keep a rooster? Fertile eggs to hatch, require HIM, as you know, but no need to wait for your hens to "set", even with fertile eggs, it is MOST UNLIKELY.
Be patient with your hens (and indeed yours are unlikely to ever become broody!) If you want hens that will hatch chicks for you, when the time is right for them, obtain a breed, such as Speckled Sussex, that are beauiful, hardy, great layers, usually quiet gentle hens, and also great setters and broodies! Meantime, enjoy your eggs as they arrive. Red Stars are great layers for their first year, maybe a little longer, and Rhode Island Reds, also are good layers, maybe for 4 or more years, but fewer eggs as they get older.
And say???,again, do you have the necessary rooster? Or were you planning to purchase hatching eggs, when the time comes? Lots to learn and enjoy learning--have fun and know that hatching and raising chicks can be addictive! Good luck.