TOKYO, April 6 (Reuters) - Japan's Nikkei share average slipped in early trade on Friday ahead of a key U.S. jobs report, with the index heading for its worst weekly loss in eight months on waning hopes of further U.S. stimulus and fresh concerns over the euro zone. The Nikkei lost 0.6 percent to 9,709.37, falling for the fourth straight session, while the broader Topix index was down 0.7 percent at 826.71.