Without knowing how many orders you will get and what dishes sell best for you where you are based it can be difficult to say because fresh is always best, i pre-cook chicken the night before, base night before and keep it covered, potatoes about 2 days at most in fridge.
For me i sell a huge amount of Chicken Tikka Masala, then Bhuna, Madras, Dopiaza, Rogan, Korma with Specials, this depends on which specials i make, Garlic specials sell well also for me.
So after a certain amount of weeks/months you can then predict roughly how many curry orders you receive and how much base/chicken/potatoes etc you will need, then saving you money and waste, so more on profit.
Will you be making rice, starters, and sides also.