Until you have proven that you can trade trough different phases of your market(s) and make consistent profits. It is easier for a scalper, who makes dozens of trades a day, than for a swing trader. A swing trader might sim trade for half a year, make good profits and think that he "got it". But because of the relative low number of trades a swing trader makes in that time, it might also just be pure luck. A scalper who does many trades per day will realize much sooner if what he does makes sense or not. But even if he seems to be consistently profitable, he should keep practicing or at least trade with small size until he has seen a few different cycles/phases of his market. Someone who started scalping NQ in February this year and traded it for one month might think: wow, this is the easiest game ever, I will pile on the money in no time ! But February and March were the exception, and only experience will tell you in which phase of the market we are in and how to adapt your trading. So there is no simple and easy answer to this question. But for a scalper I would say, stick for at least 3 months to sim, but a sim with good, realistic fills. Then, if you are consistently profitable in sim, you might switch to live trading, but I would suggest to keep the size small for the beginning. Trade 1 contract for the next 3 months, even if you make consistent profits. Then after another 3 months start trading 2 contracts, and from there you can slowly reward yourself with additional contracts, for example for every profitable month you add one additional contract.