Rec letter situation

Applying to College
1

<p>So my AP Chem teacher said that he will only write rec letters for the first 25 students who invite him to the common app and give him a list of extracurriculars (if he approves it of course). Both my BC Calculus and AP English teachers told their students to ask them in the fall if anyone wants a rec letter. These are the 3 teachers I'm considering to write my recs. So my question is: when you invite teachers on the common app, are their rec letters sent as soon as they finish, or are they sent when you send your entire app? Also, can you remove teachers you've invited through the common app?</p>