Most efficient way to learn Polish (specific plan)

Hey y’all. So long story short I am a PhD researcher who will be doing a fellowship in Poland. I know that they all speak English in the lab and that my expertise will be useful, but I would like to learn polish since I will be living there! It is the least I can do.

Has anyone developed a successful approach for learning polish in 3 months (maybe getting to a beginner/intermediate level). I mean like a specific plan; textbook recommendations, online courses etc. What do you all recommend?

I don’t think Duolingo is that effective