Investigation of galaxy formation and evolution and the formation of large scale structure in the Universe over cosmic time is one of the key science goals of the Square Kilometer Array (SKA) project. Neutral hydrogen gas (HI) forms the basis of galaxy structure formation as well as the fuel for stars and it is therefore important to measure how the cosmic neutral gas density, HI , and HI content of galaxies vary as a function of lookback time to understand the processes involved in galaxy formation and evolution as well as the formation of large scale structure. With th SKA-pathfinder instruments we will be able to begin these studies in earnest through surveying galaxies in HI out to higher redshifts ($z\geq 0.2$) than is currently possible with existing instruments on reasonable timescales. In this talk we explore various astrophysical and survey scenarios in order to optimise observing strategies with the SKA pathfinder instruments.