Is there a timeline for buying a couple ring?

We’ve been dating my boyfriend* and I asked him if we could buy a ring. I’m not asking to get married already, I just asked if we could buy a couple ring like a promise ring. He said “it’s too early”, so out of curiosity I asked him “when is it not early anymore?”

He said he doesn’t know. Did I really ask for too much?

EDIT: We’ve been dating for over a year* I’m 23 and he’s 26