Some estates can go on for quite a long time. It really depends on the nature, extent, and type of assets. If the estate consisted merely of bank accounts and other assets that could be easily liquidated, it should not take long. If it included any real estate, or an interest in a business, then it could be considerably longer and more complex.
Please note that I am a NY attorney and cannot advise you as to the application of your state's laws. For that reason, you may wish to consult with a local attorney.
Have you already probated her will and been appointed executor? Or if she died intestate (without a will), have you petitioned the probate court for letters of administration? If the answer is no to either of those questions, technically under O.C.G.A. 53-5-5, you must promptly file a will with the probate court. Additionally, O.C.G.A. 53-5-3 prohibits a will from being offered for probate after the expiration of 5 years after an administrator has been appointed or the entry of an order that no administration is necessary. (This is usually only applicable when a will is later found)
However, if you have already gone through the probate court and been appointed either exector or administrator (personal representative), there is no set timeline within which you must settle the estate. For instance, if the only asset is real estate, given this real estate market, it is not unreasonable for property to remain for sale for a while. However, part of the fiduciary duty of the personal representative is to settle the estate without unnecessary delay and without the wasting of estate assets. If a personal representative fails to act within a timely and reasonable manner, the heirs of the estate would have a cause of action against the personal representative and may even seek their removal. The question of time would come down to the resonableness of the delay and the reason for the failure to fully settle the estate. Is there a particular reason that you are asking?
If you have been appointed personal representative, was bond waived? Were you relieved from filing an inventory and annual returns? If this was not waived, you will have to file an inventory with the probate court within 6 months of your appointment and an annual return each year until you are discharged from the position. The hassle of filing annual returns usually spurs personal representatives to settle the estate as soon as possible.