Yes, it is important for you to figure it out through your own analytics. Also, it is important that you try multiple uploads in a single time frame to get a better understanding as to whether it is a good time or not. If you get low views after uploading at a certain time, it might not actually be due to the timeframe, but the content/title of the video. Point is to get an average on multiple time frames and then choose the one that carries the best average.