Working from home is not the same as being at school so it is generally a mistake to try and replicate the school-day at home.
Instead, find a new rhythm which works for you and your child / children.
For example breakfast may be later in the morning than usual, but it’s still a good idea to try and start work by 9am.
School normally ends at about 3:30pm, but at home study can continue to 5pm if there are more frequent breaks throughout the day.
In general it’s best to save any screen time until after the school work has been completed. It can be difficult for a child to re-focus on work having watched a movie after lunch.
If you child is working on maths, it might be a good idea to do this for up to 45 minutes and then take a break. If on the other hand the child is writing an essay or answering an English Comprehension it can be better to continue for over an hour until the comprehension has finished.