How long does it take an IUD to become active in preventing pregnancy after it is inserted

Angel • Married have a 10 yr old son and a 2 yr old son have had 4 miscarriages two before the birth of youngest son and two after one at 5 months 1 at 6 weeks 1 at 9 weeks an 1 on 5.24.15 at 8 weeks TTC soon
How long does it take an IUD to become active in preventing pregnancy after it is inserted? It is June 14th I had an iud inserted on May 28 and use no other contraceptives could I have gotten pregnant?