在15岁之前，他没有开始打踢足球。This sentence should be like this: 在15岁之前，他没有踢过足球。打in chinese is a verb, and here, it should be move away. And we usually call playing soccer as 踢足球。没有踢过(mei you ti guo) means never played soccer. 在…之前，we could say before, or prior to. Translate into English: He never played soccer until the age of 15. Or He never played soccer before the age of 15. 直到他15岁才开始踢足球。直 here should substitute for 至，means until. These two Chinese sentences means the same but for the different ways of expression. Hope these can help you, thanks.

He didn't begin playing soccer until he was 15 years old. =在15岁之前他没有踢过足球。 一般不会对之前的事情说“没有开始”，如果要加“开始”，这样说会比较顺： =直到15岁他才开始踢足球。/15岁之后他才开始踢足球。 踢：一般指用脚play的运动 打：一般指用手play的运动

在15岁之前, 他(都)没有踢过足球。or 直到他15岁才开始踢足球。or 直到15岁，他才开始踢足球。 打→篮球basketball/羽毛球badminton/棒球baseball/乒乓球table tennis/排球vollyball/网球tennis; 踢→足球football/蹴鞠.