The short answer
Fix the start time and the order of the day rather than the clock for every subject, protect the two or three hours when your child actually concentrates, and build in a catch-up slot so one bad day does not put the whole week behind.
Most homeschooling routines do not fail on the ordinary days. They fail on the day someone is ill, the power goes, or a child simply cannot. A routine worth having is one that bends on that day instead of breaking.
Fix the order, not the clock
A timetable that says “09:00 mathematics, 09:45 English” fails the moment mathematics takes an hour. A sequence — mathematics, then a break, then English — survives it. Children get the predictability they need from the order of the day far more than from the times.
Spend the best hours on the hardest work
Most children have two or three hours a day when they can genuinely concentrate. For many that is mid-morning, but not for all. Watch for a week and notice when it is for your child, then put the demanding subjects there and the lighter work outside it.
Leave a catch-up slot
A weekly slot with nothing scheduled in it absorbs the bad day. If nothing needs catching up, it becomes free time — which is a reward, not a waste.
Separate school time from home time
When school happens at home, the day can quietly expand to fill everything. A clear finish — a place the books go, a signal that the day is done — matters as much for you as for your child.
Review it once a term, not once a week
Every routine feels wrong in week two. Give it a term before rebuilding it; you cannot tell a routine that needs changing from one that simply needs getting used to until you have lived with it for a while.