I think the topic of learning to play in 5 years has been well covered in this thread, and I agree regarding the 2 hours per day (or even just 1 hour per day) recommendation. Learning a new skill is often all about the time put into it. People ask me how I’ve learned so many instruments, implying I’m some sort of genius. Not at all, in fact I’m slower to learn music than all of my bandmates. I just put time everyday into intentional practice. So I learned the flute in what could be measured as 5 years, though I went years without playing the instrument, focusing on mandolin, pipes, etc. Recently I got back into the flute again.
Like others here, I’ve heard the comment around focusing on one flute being recommended. As someone who just recently got to what I would consider an “intermediate quality” embouchure, here’s my 2 cents. The flute itself doesn’t really matter that much as long as it is of a certain quality. And these days we are lucky to have quality options for as little as $300 pretty commonly. Over the past year or so (quarantine project) as I’ve moved from beginner to intermediate embouchure, I’ve had 2-3 flutes on hand. Recently I even bought a flute in a different key to explore another reputed maker. What I’m finding is there is basically no difference in the quality of my playing between flutes. I currently have a more R&R flute and a more Pratten flute, so there should be relative differences, but my playing is the same if I sit with each flute for 30-60 mins.
So find a nice flute to learn on, and if you want, try other flutes too if you have the money and inclination.