2 Minute Version:
"And as my third wish, I desire a complete implementation of a Kardashev Type II industrial infrastructure around the planet's primary."
Harry Potter Version:
"Manufacturo perpetuum mobile!"
Dark Satanic (mana-)Mills version:
A century at most. Presumably, mana can be harnessed with high efficiency compared to steam or solar power by a previously agrarian civ. Moreover, magic can be used to refine tools, including tools that make magic more powerful. Since the mana resource does not need to be mined, and needs no infrastructure to develop, the magic-driven industrial revolution can proceed at accelerated pace. Even if magic is hard to master, schools of Thaumaturgic Engineers will start churning mages out on industrial scales. The artefacts they create will soon pervade every household, improving productivity at rates undreamt by our measly coal-driven industrial revolution. The only source of concern would be the social implications. How quickly would these Engineers take power, and how would the reactionary forces react against them? Think the French revolution at 10x speed.
