Here are the top articles for the month of May 2023 on HN with "agent" in the title [0]. Looks like early days for the term but with a few large hits (like the HuggingFace announcement), which suggests OP was surprisingly precise in their citation of two years as the time window.

Also, since you're implicitly questioning OP's claim to have been saying this all along, here's a comment from September 2023 where they first said the same quote and said they'd been building agents for 3 months by that point [1]. That's close enough to 2 years in my book.

[0] https://hn.algolia.com/?dateEnd=1685491200&dateRange=custom&...

[1] https://news.ycombinator.com/item?id=37626877

I'm sure you can find it in chatbot documentation from the 90s. It's a generic term carried over from non-AI chat. People responding to support chats were called agents.