How do you test if niche profitible?

I mean i know every niche can be profitible but i aint og and so far it sucks d , how do you test if what youre doing is profitible with low accounts ? Ofc if u have 100 acc you can just throw it in and see if its going to make profit after like a day or two , but what if u dont have that ammount , would you just wait for a week two ? Month ? Dont know how to make it more accurate.