Worry, worry, worry

After the ordeal with the little orange tabby, I'm left to worry about my little colony and the exposure they may have had to feline leukemia.  I'm going to research the best course of action for getting them tested again - how long should I wait after possible exposure?  On the plus side, they don't seem to have interaction with other cats that have occasionally come by.  Tabby, the male, actually seems to go out of his way to avoid confrontation. I hope it was enough to keep them safe.