It makes sense to reelase android version first, as android is most popular platform so you cover most people with it.But to spred on NA market where apple still has dominance iOS version will be needed.
That's true, if you have to choose between iOS or Android, based on the total number of mobile users available that's on one specific platform.
Teams usually dont have enough manpower, so its best to focus on one platform, in this case the one with more users, and then you can work on other.I think that this is better ,than to wait for god knows how much to get both of them released at the same time.