I just thought of something. In the opening scene before the main title scene in OoS/OoA, it shows Link on Epona, so that means it should be before MM, shouldn't it?
Not Quite. One of the endings for MM is Link riding away on Epona. So while he was gone Koume and Kotake did their thing and on his way back to Hyrule, the triforce sent him to Holodrum and Lybrinna. Note: On one of the days, I forget which, if you ride into the swamp you can see one of the hags fly off into the air from her hut. I think it is on the second day, when it rains, but it may be at a specific time. Perhaps she is flying off to find the torches...
Also, since there are multiple Links and Zeldas, who is to say there aren't multiple Impas?