I'm not sure why that's something else? If you type jj then your macro will fire, optionally deleting both the js in the trigger. If you type jo or ja the macro doesn't fire and you can continue to job or jacket.
It is best if you are in a context, eg a text box, where deletion is predictable -- but your continuing to type a word does imply that.
Otherwise you're looking at a hot key J that swallows the character, disables itself, and enables a macro with hot key triggers for every possible next character. That second macro does something if the trigger is J or types J%TriggerValue% for anything else, disables itself, enables the first macro. You'll also have to store whether the first J was lower- or upper-case, to get that right in the second macro.