It seems that you have differing opinions here and might have to flip a coin.
Unfortunately, this is a must ride for my kids. Personally, we get to DLR at rope drop (MM or otherwise) and hit Fantasyland first - once we have completed Peter Pan, Dumbo, Mr. Toad and Alice–our next stop is Nemo. We generally wait for 5min, but have waited for up to 15min. I don't think people rush to get there and ride it first, because as others have pointed out, it is a long ride, and you could do nearly three rides in that time.