This way you can't get the hardest and most special route in New Game+, but it would have been like it is in normal and it doesn't affect the actual ending anyway.
Getting the magic boomerang doesn't hinder you in anything, especially not in New Game+, since there is only one version of the ending (with a small dialogue change depending if you have a certain item or not, but that's totally just cosmetic).
However, if you ever want the alternate end of the normal ending, you indeed need to watch what you get in what order. However, getting the magic boomerang fast doesn't hurt you there, either. Only getting the actual season clothe does.