PLAN B AFTER A BROKEN CONDOM

Me and my boyfriend were having protected sex and everything was going great up until he pulled out. At first it wasn't anything abnormal but then he saw his cum on his sheets and looked at the condom and it was completely destroyed. We immediately went to get a plan B pill and 20 minutes after we fucked I took the pill. His cousin said we should've waited a day because if it was taken too soon it would be ineffective. Is that true? PLEASE HELP!!!