When you tell people you've written a book, the most common response is something like, "Oh, how nice for you," with or without a discreet (or not) eye roll. But for the rare few who are actually interested, the inevitable response is, "When can I buy it?!"
Sometimes that's harder than the eye roll. Because then you have to explain, and the publishing industry makes little sense to the people involved in it, let alone an outsider.
The real answer is: Possibly never. Maybe even probably never. After that it's: well, if my agent and I are lucky enough to sell it, you can buy it approximately two years from now. And it will undoubtedly have a different title and not be exactly the same story I just described to you, so you'll have to remember my name.
And that's when you lose them completely.
This is a waiting game. You query and you wait. Your agent queries and you wait. And wait and wait and wait.
You have to hope readers are still waiting when it's done.