We're not sure exactly how long you're going to have to wait between pre-registering and actually getting your hands on the game, but on iOS there was about three months between registration and launch, so expect something similar.
Android vs iOS
The graphics and gameplay look pretty much identical on the Android version of Super Mario Run, and the World Tour, Toad Rally and Kingdom Builder elements of the game are all present and correct.
The game has certainly attracted a lot of attention on the iPhone, with over 50 million downloads, . However, how many of those users actually paid for the full version or are still playing the game isn't as clear-cut.