Well some quick math: In 15 hours playing time you could do MM/Lost City and get 60 Attack/Strength.
From there it's around 25K xp/hour for pures @ rock crabs so 100 hours is 2.5M xp - 2M xp needed for 80 so it can technically be done in 5-6 days of 24 hour botting.
A good few months if you wan to make a maxed staker. Or you could spend a month making a pure staker. There's even a better alternative. You could buy a staker lol