Move them soon. JDs grow pretty fast. I would suggest moving them into a 75g with your choice of two of these:
Striped or spotted raphael catfish
brown hoplo catfish
medium pleco species (I like Panaque nigrolineatus)
You could probably also get away with almost any other species that grows to between 6" and 12", but I would go with those listed above because their armor will protect them in case the JDs get nasty. BTW, start praying now that your JDs will not try to kill each other when they get a bit bigger (more space and clearly defined territory borders will help).