No, In short words 100$ is not enough to start day trade. Again you can start by this amount but you can not earn profit from it except lose. Suppose you start the trade with 100$, how much you want to get profit from it? Basically, for a day trade, we should not expect more than 1-2% per day. So for 100$ 1-2$ per day is enough for you? and you have to mind that there is an exchange fee in this profit. And you can not win every day, sometimes you will lose more than profit. Thus you can lose all of your capital.