I have some good ideas for books and I'm ready to start querying agents. Just curious if you can tell me about how long after an agent accepts me will I have to write the book?Are you talking fiction? Fiction books need to be finished BEFORE you start querying agents. Or publishers. You need to write it. Then have some readers go through it—not family or close friends, but discriminating readers who know something about what's selling today. Make changes based on your readers' suggestions. When your book is as perfect as you can get it, then you're ready to start querying.
If you're talking non-fiction, if it's your first book, I'd suggest you be fairly close to done before querying. If you have a platform, do a lot of public speaking on your topic and are generally known as an expert in the field, you might be able to get by with an outline and the first few chapters when you query. But plan to be able to finish the book in 3 to 6 months—the sooner the better.
P.S. I'm out of questions. Please send more.