I'm still using some evolved 2* girls, and it's fine. Most important part is: Can you 3-medal the event maps?
You can keep replacing your girls with more rare girls and get stuck with non-optimal teams for ages, waiting for gold and manyus, or get the girls you actually use up to about lvl 30 evolved (which is relatively cheap and easy to do with 2* girls), and then start replacing them with the girls you get from events.

ideally you should save them for a girl you want, believing in the chance of getting her, unless nutaku puts a really tempting limited gacha (like the limited 2 slyce type gacha) and you feel that you have more chances of getting something good there

Personally I only evolved 2 3* before I got 5/4s to fill out my team. My advice is to not evolve them until you have evolved and lvled your 5/4. Remember you get a new 5* every 2 weeks (events) and gacha seeds should eventually fill out your team with 4*. Also if you do decide to evolve them make sure its to fill in the weak spots (such as magic or slice) of your team since you cant really choose which 5/4* you get.

Originally Posted by Drip

Most important part is: Can you 3-medal the event maps?

Does 3 out of 8 count? XD

I'm at the point where i'm evolving and giving affection items to 2* girls because most others are already done or waiting for their colour manyu.

As of currently i do not use bronzies anymore but i had them for a long time and Hydrangea is one hell of a bronze along with many others. Frankly, there is nothing bad with evolving 3*s because they pack a decent punch and you can clear this whole bloody game with a team of 3*s.