Yes. It is mandatory to reach the rafting start point at 8:00 am.
River rafting in Kolad is dependent on a dam controlled river. Water is released from the dam for a few hours everyday in the morning. Flow and rapids for river rafting are generated when the dam gates are opened.
Once the dam gates are closed, rafting is not possible. If you reach late, there might not be sufficient flow in the river for river rafting to happen. Hence it is mandatory to reach at 8:00 am.