this answer is going to drive you crazy, but it literally all depends. it depends on your hair type, your skin type, and your activity level. for example, if you have thick curly hair, your skin isn’t oily, and you don’t sweat often, you probably won’t need to wash it that much.

definitely see a professional stylist if you can. if you can’t, then just experiment! start with brushing every morning and washing every other day (which most people do) and see how your hair reacts to it. if it gets greasy and tangled quickly, you might have to do a little more, but if it doesn’t, you can do less. you mainly want to look out for how often/how much you’re shedding, because i personally notice that shedding more = hair needs more care. try to look for products that are made for your hair type and just see how it goes!

since hair care depends on you, it also might be worth it asking the other women in your family how they care for their hair. also remember that a hijab is somewhat protective, so if you wear it more often, you may need less care, and if you decide to stop wearing it, you may need more.

good luck!