when did he begin his career?
During 1901 when he joined the Northern Circuit
William Finlay, 2nd Viscount Finlay
1901 and joined the Northern Circuit. 
when was william finlay, 2nd viscount finlay born? 15 October 1875 who is he? A British judge and peer
wiki:3047751
William Finlay, 2nd Viscount Finlay [SEP] Early life and career
Finlay was born on 15 October 1875 in London, the son of the Scottish barrister Robert Finlay and of Mary Finlay, "née" Innes, daughter of Cosmo Innes. Robert Finlay, later the first Viscount Finlay, later served as Lord Chancellor between 1916 and 1919 in Lloyd George's government. William Finlay was educated at Eton and Trinity College, Cambridge, where he placed third division of the third class in Part I of the classical tripos in 1897. He was president of the Cambridge Union in Easter term 1898. Finlay was called to the bar by the Middle Temple in 1901 and joined the Northern Circuit.