And if you also going to launch in EU/Australia/Canada, you will have a nearly 50-50 split of ios and android users on a platform neutral app.
So the classical logic of implementing on iOS first doesn't really apply anymore. Now its more, implement first on the platform you are comfortable with but don't forget about the other platform because there is a equal amount of money to be made there...
PS: Data excludes low end iOS and android devices. (< SE, old iPads/iPods, old and cheap android devices). These devices have extremely low conversion on both platforms anyway.