I would actually recommend that instead of a Cuttlebone in your Conure's cage, that you pick-up an Avian Mineral-Block for him and hang that up in his cage...Avian Mineral-Blocks provide not only Calcium and Phosphorous like the Cuttlebones do, but they also provide other very essential Minerals/Vitamins as well, AND they keep their Beaks trimmed too!!! My Green Cheek Conure, my Senegal Parrot, my Cockatiel, and my Quaker Parrot all have both a Cuttlebone and an Avian Mineral-Block inside each of their cages, and yes, the Cockatiel uses both of them, but the other 3 don't pay much attention at all to their Cuttlebones, BUT THEY LOVE THEIR MINERAL BLOCKS and use them every single day! They each use them pretty much every time they eat, especially if they eat anything sticky or wet, like their fresh Veggies/Greens, they use them to wipe their beaks off...But they each also just go over and nibble on them a bit most days, so they definitely prefer their Mineral Blocks to their Cuttlebones, and they provide the same nutrition plus some...
I buy my Avian Mineral-Blocks at either Petco (they sell both a pink, Strawberry-flavored Mineral Block and a yellow, Pineapple-flavored Mineral Block), or at another independent Pet Shop/Livestock Shop/Bird Shop (it's HUGE), who sells Avian Mineral Blocks made by a company who makes them in all kinds of different colors and flavors...Right now they each have Mineral Blocks from Petco, and they love them...
The really nice thing is that I never have to trim/file their beaks at all because of the Mineral Blocks, in-combination with their Cement/Nail-Trimming Perches that they also each have in their cages...So I'd highly recommend that you pick up an Avian Mineral Block for your Conure and hang it up in his cage in a different location than where you have the Cuttlebone located...I have their Cuttlebones on one side of their cages and their Mineral-Blocks on the opposite side of their cages, that way they will always have access to one and they always see them, so they are more likely to use them...And I always hang both their Cuttlebones and their Mineral Blocks on the cage-bars at the end of a perch, preferably a perch they sit on often, so that it's easy for them to just walk right over and use them, rather than putting them somewhere on the cage-bars where they have to purposely climb to get to them. I see them all the time sitting on their favorite perches and then suddenly they just walk right down the perch and have a nibble on their Mineral-Blocks, then they go back to the other end of the perch, and they often keep going back and forth to and from their Mineral Blocks...I guarantee your Conure will use an Avian Mineral Block quite a bit, and it will not only provide him with well-rounded Nutrition, but keep his beak nice and trimmed and dull on it's tip, instead of him having "Needle-Beak" all the time...They only cost $2-$3 so well worth picking one up for him, and I'd also just leave his Cuttlebone inside of his cage as well, because you'll probably find that once he starts using the Mineral Block on a regular basis he'll also start using the Cuttlebone more s well. Just make sure you put both right t the end of perches he uses often.