Kyleena IUD

I had Kyleena inserted on on March 13th. After the insertion I had the regular spotting. Then my period started March 17th, 3 days before it was scheduled. I expected an irregular cycle but what I don’t understand is how quickly it was supposed to take effect and how long the irregular cycles would last? I have now had my period for 12 days. It’s not just spotting either, it’s like a full on period. Advice and insight is greatly appreciated