Okay.. so, I want to turn my Common Kumos into a Nostalgic Kumos. It's my understanding that I take my Nostalgic Kumos Instructions to Vanya.

He'll ask me for three items. (I've got Turquoise Scrap of Fabric, Stuffy Typewriter, Pink Scrap of Fabric and I'm saving up for the Plushie Makers Kit)

I bring him those items and he rewards me with a lovely Nostalgic Kumos Toy. And in order for my active Kumos to become a Nostalgic Kumos, I'll need to bring him the Nostalgic Kumos Toy and the Essence of Melody.

That's what I get from reading this post. If I'm wrong, let me know! o:

My question is: Can I keep that toy (in my vault) and come back with the Essence of Melody once I save up for it? Or, is there a time limit and I'll have to come back with the Essence of Melody in that moment?

Actually, aside from the plushie makers kit, he will ask you for random items from thimble and co. You can keep the toy in your vault and come back with essence of melody at any time.

Ohh, I see! o: Okay great, glad to hear there's not a time limit. Thanks for your help!