I also use a systemic insecticide several weeks before I plan on bringing them indoors. Some bonsai enthusiasts feel that no fertilizers are needed after later summer. The use of fertilizers with a high nitrogen content is detrimental to the health of the tree. You want to avoid developing new shoots that will not harden before winter. On junipers add a small amount of agricultural lime to promote good color next year.
Insects are as busy now as ever and diseases are ever present.
Spider mite population can be controlled with Kelthane. You have always promised to do the fine wiring needed on your bonsai. Well now is the time to honor your promises. If you fine wire now you can leave the wire on until spring. But, make certain to remove all wires in early spring or your trees will be damaged.