Eh, probably not a few centuries. I could be, IDK, but I don't think it makes sense to quantify like that.
We're a few major breakthroughs away, and breakthroughs generally don't happen all at once, they're usually the product of tons of minor breakthroughs. If we put everyone a different their dog into R&D, we could dramatically increase the production of minor breakthroughs, and thereby reduce the time to AGI, but we aren't doing that.
So yeah, maybe centuries, maybe decades, IDK. It's hard to estimate the pace of research and what new obstacles we'll find along the way that will need their own breakthroughs.
If an AI can effectively do your coursework, why wouldn't AI replace you in the industry?