John 16:7-9
7 Nevertheless I tell you the truth. It is to your advantage that I go away; for if I do not go away, the Helper will not come to you; but if I depart, I will send Him to you. 8 And when He has come, He will convict the world of sin, and of righteousness, and of judgment: 9 of sin, because they do not believe in Me;
John 6:28-29
28 Then they said to Him, “What shall we do, that we may work the works of God?”
29 Jesus answered and said to them, “This is the work of God, that you believe in Him whom He sent.”
Water baptism in the early church was an outward sign of faith in Jesus.
The spiritual aspect has already happened before the physical aspect.
I do feel however that the physical aspect really does set a marker in a believers life.
To be honest I also feel they anyone who places their faith in Jesus should be baptised straight away.