I'm in the same boat. Ivy is one of the girls I'm saving FGs for.
Haven't been playing too long but my waifus right now are Black Baccara, Robinia, Ivy and Lily. Really glad for the Black Friday deal letting me snatch my 6* waifu and Robinia's event is happening. She's not the best unit, but she does get a bloomed and I'm a sucker for the uniform.
Guess we'll see how my waifu rankings shift as more girls come out.