Depending on the age of your audience, it's a good idea to have a fixed day of the week and time when you upload so that people can expect when your next upload is. I follow some people on youtube and I know exaxctly how late their video is uploaded and get onto youtube to watch it.
Also, when you have a following, you'll see that there are peaks in traffic, usually at the same time every day. When you launch your video, you should aim for a time when most of your subscribers are on YT. The first 24 hours of the video is critical for the algorithm to decide how much they will promote it. View velocity is also very important for this. So if you upload 2 hours before the peak, you will have a lot of volume to your new video and you have the velocity as well.