Adds forecast changes from Goldman Sachs, J.P.Morgan and BlackRock, more details on Barclays Dec 14 (Reuters) - Wall Street brokerages brought forward their expectations for the U.S. Federal Reserve's first interest rate cut, with Goldman Sachs now seeing a March start to the easing cycle, after the central bank struck a dovish tone overnight. Barclays believes cuts could begin sooner than its June projection if monthly inflation prints continue to come in softer than its forecasts. Asset manager BlackRock's investment arm sees Fed rate cuts coming in "around the end of the spring into the summer."