It is not mandatory use of demo account. If you believe that you rule a good trading skill you can open a real account immediately. However, it is recommended to use the demo account and practice trading first.
Go ahead with small live account instead demo. You will not learn anything in market with demo account. You will not feel what exactly the live trader feel in the market, and that will drag you behind the road to become a day trader.
Of course always practice good trading behavior during trading, not to overtrade, not to oversizing the lot size, not to trade when you are bad mood, market are dead, bank holiday. You ll need to keep conscious of anything related to the market, anything. Don't simply look at the chart and pull trigger by following some people ideas or strategies, you need to have your own perspective in trading, you need to understand and know what you are doing.