Well, as we've discussed this sidequest before, I think it's pretty much understood that the idea is basically accepted, we've just gotta work out the details.
Something I still don't understand is why the player isn't allow to know about this quest until after the forest temple. This seems like it would make it less likely that they would hear about it at all, because they'd go into the musical triforce once before the forest temple maybe, then they might not go back in after because they've already seen what's in there. Why not have it like this:
During the day, Jimi plays in the street on the poor side. If Link talks to him at any point, he'll tell Link he works at the Musical Triforce, but he thinks his sound would be better if he were backed up by a four or five piece band. You can't talk to Jimi at night because he's busy playing guitar.
Then, throughout the overworld, will be four or five musicians, perhaps one in Hyrule field, a Zora guitarist at lake Hylia, a Goron musician on the mountain, etc.
If you haven't talked to Jimi, they'll just say that they play their instrument and would like to be in a band, or that they're thinking of moving to Hyrule town for music opportunities. But after you've talked to Jimi, they'll be like "I wish I could be in a band... What? They're looking for musicians in Hyrule town? Awesome, I'll go", or something like that.
This way, the purpose of the restriction you're imposing of Jimi not talking to Link about the band until after lake Hylia, that Link can't complete the sidequest until later in the game, is accomplished by the location of the traveling musicians, you can't complete it until you can gain access to where they're located.