You have it right. Get the experience first then fly airliners. I cropdusted, flight instructed, flew charter in prop and later jets then corporate then with many thousands of hours flew with over 100 people in the back. That way you can learn in little steps, not quantum steps.
In a C150 I would sample a little icing and IFR to build confidence and experience. I always had a way out. Nobody should go from flight school to the right seat of an airliner. What if you have a weak captain? Maybe he is sleeping and you have another new FO in the other seat while he is taking his break. The FAA did a good thing changing the rules.