If it's an ale yeast at typical ale fermentation temperatures, if you've pitched enough yeast and aerated your wort properly, then, yes, it's possible that your yeast could take off relatively fast.
If you saw bubbles much before 8-12 hours after fermentation, though, it's more likely to just be dissolved air escaping from your beer.
It's not at all unusual for ales to (mostly) finish fermenting in just 2-3 days.