That's not terraforming. That's a biodome or a subterranean enclosed environment. Note, biodome technology hasn't been achieved here on Earth. Nor does it make sense to house settlers on another planet in this manner as they would require constant supply.
Yes, true terraforming would take a long time. But if we're talking about leaving Earth as space frontiersmen & women to establish permanent settlements it's really the only viable option.
Your method is fine for mining, etc, but not permanent settlements.