Burping Help??

Danielle
My LO is 2 weeks and just starting to fuss terribly after I nurse her. Often the crying bouts end with gas/burp/poop...but it's awful until we get there. How often should I be burping her and for how long? She usually nurses for 25-30 minutes.  Can I wait till she's done to burp? Or should I stop her mid- feed?