The best time to stream on Twitch is when your targeted audience are on the roll. You can stream on twitch any time of the day. Twitch has a large audience who are on it 24 hours, 7 days a week. It depends on what kind of audience one is targeting. Whats the best time for your audience, which region of the world you are targeting etc.
If you are aiming for a US audience to watch your content. You need to target them when they are awake. You can use tools such asor just browse Twitch itself to see when the games/content you want to stream is popular. You’ll see patterns forming and be able to work these around your personal schedule. Some games are popular at weekends as opposed to weekdays and vice versa. Because the whole family may be watching it.
On the weekdays, peak viewership is usually at around 6PM to 8PM at an average of 1.6 to 1.75 million viewers. It’s very likely because this is when adults just get back from work or kids just finish their homework and start to wind down. At around 8:30 – 9PM it starts to go down.
Other factors to consider before streaming is the kind of game you play, how affected you are by other streamers coming on, going off, avoid ‘larger streamer’ times. Try different times and you will come up with the best time that works for you.