4000 watch hours is achievable around 6 months time for an average channel with 1k. As a YouTube partner program member, here are my best tips to achieving that:
1. Make videos that people want to watch for a very long time (Tutorials, Documentary series, Spicy content and detailed content, ETC). Gameplays can achieve this, but the key is to keep your viewers engaged throughout your video. My personal tips is to make a one minute intro explaining how the video will be exciting. It usually increases my watch hours a video. From there, i try and pack content in so that way my videos seem exciting and keep my viewer watching. If doing gameplay, its good to do twists and turns and add your own commentary + an intro, which usually increases watch time.