In your rush to cut & paste you did not even read what is written after this statement
"At the beginning of April, the Army Chief called me on telephone to say that the Government required Eastern Command to move immediately into East Pakistan. I protested that this was impractical (because troops who had earlier been trained for mountain operations would require to be retrained for riverine operations. There were large, wide, tidal rivers, there was no bridging equipment and the coming monsoons would make access to unbridged rivers extremely difficult).
`General Manekshaw then asked by what date we would be ready. Provided we got bridging and suitable weapons and equipment, I said, we could be ready earliest by 15 November. This would leave adequate time after the monsoon for the terrain to become passable. Manekshaw, upset and impatient, replied that he would get back to me.
Read the report in full and you will see that it was end in the end of April a political decision to intervene in end of 1971 was taken.
So dont give the impression that in April the Indian army was already in position … they are a professional army and had planned their operations … not like Pakistan …