So if you only visit your house once in a while, it will take a LONG time to finish. On the number of times you leave the area. The amount of time it takes for stewards to furnish your house depends Since you said that some furnishings have already appeared, it is probable that you did not waste your gold, and that it is just taking a long time.
The UESP wiki page states that the process of paying a housecarl to furnish a home is a very slow one.
