Jesus Himself was baptised but John in the River Jordan age not ago of 30, just before the beginning of His public ministry, giving an example for His followers.
Jesus told His disciple that they should go and make disciples of all nations, baptising them in the name of the Father, the Son and the Holy Spirit.
The disciples obeyed Him and preached the gospel. Those who believed and repented were baptised in water.
Who should be baptised?
Anyone who has repented from their sins, believed in Jesus as their saviour and decided to follow Him as disciples, should be baptised in water.
When should I be baptised?
As soon as you have believed! You shouldn’t delay.