My advice is to only evolve your 5/4* girls. Get your 3* to around 30, which can be done with the crappy manyu, and then star evolving your 5 and 4 star girls. I'd recommend getting then to about 30-40 after evolving them as well. Ideally you should only use the matching manyu on each girl so you can maximize your xp gain. Also keep in mind every 2 weeks you get 1 free 5* from events and you should get a slow trickle of 4* from gacha seeds as well. If you get to the point where you've run outa 5/4 to evolve do a 3* of whichever type you have the least of so you can balance out your teams better.