Williams didn't start at 18, right before his fight with Wright they were talking about how his bus driver recruited him. I don't know any 18 year olds that take a school bus :rofl unless you mean first amateur fight? which im not sure if it was 18.
hmm says... My lil bro said Hopkins started at 6 and Tarver at 8. They both started their pro career in their 20s... Larry Holmes (not sure) Jess Willard near age 30 Mundine at 25
Bernard Hopkins - He started boxing late since he was locked up when he was younger. Nate Campbell also started late at age 26 i believe and became a champion at 135.
Hopkins had over 50 amateur fights before going to prison. Fan for some reason thought that he had little to no amateur experience .
Williams was not 18.They did a piece on him just the other day to fill space between the arreola fight and his fight. he was 10