Car Repossed

If I signed contract on 9/7/11 at a pawn shop. My first payment was to be on 10/7/11, but they kept documents dated 8/31/11, on which date I came in for $100.00. They knew I had just went to work. My question is If I had not spoken to them, nor received any letter. Regular or certified. They made no attempt to come to house. Is there a minimum time line to reposses. They took car on 11/20/11. I figured I was 13 days late, and was planning on going in on 21st, since I work out of town in a remote town with no cellular service. I do not get home till after 7 pm. in which they are already closed. 30 years ago when I repo'd cars for Ford Motor Co. (Utah),We had to wait 90 days, and have proof of certified letter. How long or soon can a Co. take car with no forwarning.