Everyone presenting a conference paper likes to have a generous commentator who will discuss their contributions in a positive light, and will point out inevitable shortcomings in as gentle a way as possible. The best way to forfeit that is to do what a paper presenter once did to me: turn in a paper the evening before the panel, which is 70 pages long, and has no citations. (This was not at LSA, but at a history meeting.) The best thing for a commentator to do in that circumstance is usually to note the time the paper arrived, and then simply ignore it. But what if you're a paper writer, and the deadline is approaching, and you find you are going to be late? This happens to the best of us. Here are some suggestions about how to handle it:
1. As the deadline nears, if you realize it will be impossible for you to meet it, contact your panel chair and commentator(s) to tell them that the paper will be late. Do not wait until they track you down.
2. Give your chair and commentator(s) a realistic estimate of when you will be sending in the paper. Then be sure to send in the paper by that date. Your date should not be less that two weeks before the panel. Preparing a good comment, as opposed to a seat-of-the-pants comment, takes time. Sometimes I look up sources the author is citing, for example. Two weeks often works for me; less time becomes a serious problem.
3. Besides an apology, what do you say? If you have a very good reason, especially for the rare circumstance when you'll have to send in a paper with only a week to go, say it in your email. I had a baby last month is a good excuse. I'm on vacation (yes, I've been told that) is not an excuse. Don't provide a laundry list of excuses -- this never makes you look good. And when faced with a real crisis, your co-panelists will understand, but there is no need to provide too much personal information. "I am in the middle of a family crisis" will do it, rather than "my partner just left me and took the kids," unless of course your commentator is a personal friend. Same with medical details.
4. Do not send a preliminary paper, following up with a final version the week of the panel. Send one copy as early as possible.
5. If much of your paper is finished, but you haven't been able to write a particular section, you might insert a brief description of what will go in that section, and what sort of research will support it, rather than waiting to write it up and sending an unconscionably late paper. The paper is a draft, after all, and not a polished, final product.
6. Present at the panel the work you've sent your commentator(s), not work you didn't have time to get to until after you sent the paper in.
Presenting a conference paper is a great way to create and build scholarly relationships. To do this, it is important to avoid bad conference behavior, like the last-minute paper. If you're presenting at the LSA, and you haven't sent in your paper yet, you are already late. But it is not too late to save face. Best of luck!