I’m sorry for having missed answering this question of yours. I was surprised seeing it only today despite the fact that you posted it in the Forum over five months ago.
The sentence you presented, “Just think, this time next month I have been working here for ten years,” is constructed in the wrong tense. The two time frames involved in the action described—the future “next month” and the likewise future “have been working here for ten years”—constitute the
future perfect progressive tense, the form of which is as follows: (Subject) + (“will have been”) + (present participle of main verb) + (time relation to another future action, expressed in the present tense).
The correct construction of the sentence you presented is therefore this: “Just think,
this time next month I
will have been working here for ten years.” The sentence describes an action (the “future perfect progressive” component) that, reckoned from an earlier point in the future, continues uninterrupted beyond another given point in the future. It differs from the construction of
plain future perfect sentences, which has this general form: (Subject) + (“will have”) + (past participle of main verb) + (time relation to another future action, expressed in the present tense). Thus, if corrected to be in the future perfect tense form, the sentence you presented would take this form: “Just think,
today I
have been working here for ten years.”
I see now that I missed taking up the future perfect progressive when I did a review of the perfect tenses last January 2 (
“A full-dress review of the perfect tenses”), discussing only its four most common scenarios. To round up that discussion then, just add the future perfect progressive tense as the fifth future perfect scenario.
