In general this is not a definite time for all traders and beginners because everyone practices with his own technique and spends a different time than others per day, but I think 2 to 4 months is a good period and enough to practice in the demo account before trading on the original account, but if you notice that you still need more time then of course do and allow yourself to take the time to study and depend on the trader, how far they are following the demo account. I concluded that 3 months was enough but admitted that if traders did not get trust, they were obliged to collect examples by assessing themselves and their understanding. Everyone who is not equal also needs an unmatched situation to know the trading technique.