<p>The earlier you ask your teacher the better. That way, they have more time to think about what they're going to write. If you ask them a week before it's due, they're more likely to say no, or write a less-than stellar recommendation.</p>
<p>One other thing to keep in mind: Certain teachers tend to get more requests for recommendations than others. Often, these types of teachers put a limit on the number of recommendations they can write, simply because it takes time. So, If the teacher(s) you have in mind fall into this category, it is wise to ask them NOW (or in the next few weeks) as there is a likelihood that they may turn you away if you ask after they've already agreed to do the number of recommendations they can realistically handle.</p>
<p>If you're applying early decision, you should DEFINITELY ask and give the forms to teachers no later than the end of this month (September).</p>