Chemical compound soup, natural reactions -> natural reaction produces the first reaction which is self replicating (I'd assume RNA here) -> self replication reaction dominates natural reactions (to what order, who knows) -> self replicating reaction mutates into a form that better harnesses energy from environment (your metabolism) -> metabolic empowered reaction dominates -> etc
From a primatives perspective, it seems reasonable that the first "evolutionary" advances would have all been incredibly preferential. In the sense that they had no competition with similar capabilities.
Imagine the first organism able to metabolise something (sunlight?) for its own purposes. Against "organisms" that were still waiting for chance to bash them against the right compound.
I actually don't know what a flask full of RNA will do when left to its own devices. My science education has gaps. However, really basic chemistry says that you can't create big molecules from small molecules without some sort of energy gradient, because the big molecules have less entropy than the small ones.
When you have a flask full of stuff, what it does spontaneously is go to thermodynamic equilibrium. If you want a self-sustaining reaction that creates specific big molecules over and over, you need to keep adding energy.