The time frame it takes to build a 3000 square foot house depends on if a builder is doing the work or the homeowner is doing most of the work and the weather conditions.
If the owner is doing most of the building of the house it may take them 2 to 3 years from start to finish.
However if a quality builder with lots of other construction workers are working on the house it can take as little as 6 months from start to finish to build the house and have it ready to move into.
Of course bad weather can affect the time it takes to build the house so expect a 1 year to 1 year and 6 months for a quality home build from start to finish.