This really depends on RH of your environment. I never put a fan or have circulating air on my drying buds, you really dont want your shit to dry too fast. however if its in the middle of summer and you have tons of humidity then I think circulating air would be appropriate. but obviously its the not summer right now no matter where you are. so im gonna suggest you just let them hang dry without a fan. I like to sweat my buds when the outsides become too dry but theres still a lot moisture on the inside, everyone has their own way to dry and cure so your just gonna have to experiment and find out what works best for you.