The time that an 8 year old boy should be in bed at night is by 7:30 PM to 8:30 PM at the latest.
8 year old boys need at least 9 hours to 12 hours of sleep for optimal health and functioning, so the 7:30 PM to 8:30 PM bedtime is the best time for the 8 year old boy to be in bed to get the proper amount of sleep.
If your 8 year old boy needs to wake up by 6:00 AM to 7:00 AM for school, then an 8:00 PM to 8:30 PM allows for the 8 year old boy to get adequate rest.
9 to 12 hours of sleep per night is the recommended amount of sleep for an 8 year boy and school aged children 6 to 12 years old.
And consistent bedtimes and a 20 minute to 30 minute calming routine like reading, bathing, showering etc, can help the 8 year old relax before bed and wind down.
Also the 8 year old boy should avoid screens for at least 30 to 60 minutes before bed.
If your 8 year old son needs to wake up earlier like 5:00 AM to 6:00 AM, then they should go to bed earlier.
And to help your 8 year old get to sleep easier, ensure they are getting plenty of physical activity during the day, which helps wear them out and makes them tired for the night.
Keeping a similar sleep schedule and bedtime for your 8 year old boy on weekend also helps them maintain a healthy sleep cycle.