Let's say your wish comes true. You meet with Mr. Dreamagent (or editor or publisher) at the conference and he requests a full manuscript. If you're finished with the book---and it's polished and gleaming and ready to grace his desk----no problem, right?
But, what if. . .maybe you said it WAS finished, and you'd love to send it, BUT. . .
"I'm leaving for Bangladesh (or some other place with unreliable wi-fi) as soon as I leave this table and I won't be able to send to you for six or eight months, it's monsoon season, you know and . . . "
"I need to fine-tune it a little. Can I send it to you next spring. . ."
"My computer crashed right after I printed theses pages and it might be a while before (insert Best Buy, Tech Support, etc right here) can recover my manuscript. The whole thing was lost and . . ."
These are all EXCUSES or BIG, FAT LIES, depending on how honest you are with yourself. Finished means FINISHED. Not just your story has a beginning, a middle and an end, but done. Finito. Mr. Dreamagent has heard all these lines before, and more besides. He'll be asking himself why you can't send it from the hotel before you leave on your whirwind world tour, why you didn't back up your work, how come finished means not really, completely finished. You are not getting anything past Mr. Dreamagent and in the long run you're only hurting yourself and your reputation.
Agents, editors and publishers are looking for something to sell. They can't sell a book that isn't finished. If your book is still in the works, admit it. Be honest. Tell Mr. Dreamagent where you are in the process and see if he's still interested. Be realisitic in your timeline. Don't promise to mail it next week if you know that's an impossibility. If you tell Mr. Dreamagent you'll mail it next week, and for some REAL reason you can't, email and explain. (NOTE: I'm NOT telling you to write a two page email re: your loved one's entire medical history, including the juicy parts---more like "A family health crisis prevented me from mailing the manuscript as planned. It will be posted on Monday.")
Lying to a person that you hope to develop a professional relationship with, right off the bat, is not the way to go. If you snag Mr. Dreamagent, you want to create a relationship that's honest, open and cordial. In order to create a good relationship with Mr. Dreamagent, you need to make sure you live up to your word, meet deadlines, and deliver as promised. Hopefully, he'll do the same. It's kind of like a three-legged race---you're in it together.