My experience in the hobby is secondary to my experience as a General Contractor. Like I said, I don't know why you raised the concrete to begin with. I would have left it on the original concrete slab. However, since you did raise it, I would let it cure for at least a couple of weeks before putting the load of your tank on it. If you mixed the pour to a minimum of 3000 psi (standard rating for a home slab) and used rebar like you said, you should be fine.
Keep in mind, the way a home is built from the ground up starts with the footings below the frost line. Then you either pour or form your foundation walls. The sill plate sits on top of the foundation wall. This sill plate is typically a 2"x6" pressure treated board that runs the perimeter of the foundation wall. The entire house structure sits on that sill plate. The sill plate is basically the same width (6") as your foundation wall (see pic). The sill plate carries the entire weight of the home and sits on the concrete foundation wall right at the edge. No different than your setup.
Bottom line, again, I see no reason your design wouldn't work.
