That's beautiful. I love the thought of being baptized in the river. I was baptized in a lake that meant a lot to my parents and I don't remember feeling the weight of what I was doing. I wish it had meant more to me at the time.
I don't think I grasped the total picture when I was a kid either.
Regardless of the age, I don't think the full weight is known until we've developed a mature deep relationship with Christ. But being so young of course we did not. But I tell you, I still can't grasp the total picture. The more I learn them less I understand sometimes.
I think that is the beginning of understanding; understanding that we really understand so little. If we can just trust and leave the understanding to God.