Greg, I really like your answer but I think there is one minor issue. The IC's influence on the MC has to occur during the timeframe of structural act 1, within the story's timeline. So it's not enough for it to affect the MC once they do meet, if that meeting occurs during after any signpost 2s (structural act 2)
That said, perhaps the IC can influence the MC indirectly during the proper timeframe. (News reports, phone calls, messages, etc.)
@Lakis, to answer your question, I think they're fairly common. Black Panther, for example, uses Nakia before Killmonger gets close enough to T'Challa. That might be a good example of how to handle the relationship story too. There's also Trinity in The Matrix -- I think she's mostly RS.
One suggestion -- you might want to develop your outline to the end (at least as much as you plan to) before trying to figure this part out. You might find that once your author's story-mind can see the whole story, a stand-in IC (or another solution) presents itself for Act 1 almost automatically. Possibly with the right RS aspects there too. Since Dramatica is just helping us get to what our narratively-tuned brains appreciate, your muse might provide the right pieces for you.
Part of the reason I suggest that is that Jim has said getting IC hand-offs right can be a real pain. So if you have to do it, I think it might be better to feel your way through it, at least on the first draft. (Actually, speaking of first drafts, you could just ignore this "rule" that there has to be an IC & RS signpost 1, and skip them for now. After your draft is done you might find that you put IC & RS signpost 1s in perfectly somehow.)