Follow course query

Hi, I had a course loaded on the edge 25 that started 5 miles from home. I left home having started 'do course' and rode to the start point. Soon after the start of the course i looked for navigation to find edge had stopped. I started it again and selected 'do course' and set off. From then on the course was shown but the turn alert only showed an acute 'turn right arrow' (that i later realised was a turn round instruction) with a rolling countdown 999-1 yards. The problem seemed to be that i had started the course past the start point. I expected it would register I was on the selected course and continue from that point. Can any one tell me what i did wrong?