How many hours should I spend on my history coursework?

It's worth 20% of the overall grade. My history teacher told us we should spend a total of 100 hours on it (including reading academic books, collecting sources and writing), but I'm sure thats meant to be aspirational as I'd need to work 8 hours a week to get it done before the deadline. Realistically how many hours should it take? Just so I know how many free periods I should dedicate to it (I'm aiming for 3 A*s btw so it want to get it right)

It's worth 20% of the overall grade. My history teacher told us we should spend a total of 100 hours on it (including reading academic books, collecting sources and writing), but I'm sure thats meant to be aspirational as I'd need to work 8 hours a week to get it done before the deadline. Realistically how many hours should it take? Just so I know how many free periods I should dedicate to it (I'm aiming for 3 A*s btw so it want to get it right)