EA Studio needs these 300 bars so the indicators used in the EA will have a sufficient lookback period so they will start working correctly over the time frame you are interested in observing. 300 bars where each bar is 4hrs indicates you need at least 3 months of data history. Are you using your broker’s historical data? If so you need to maximize the broker’s history data in MT4. If you don’t know how to do that I will provide a link to a video to show you how this is done. The other option is to use the Premium Data in EA Studio.
Alan Northam