The procedure for voluntary winding up means members or directors initiate the winding-up process themselves, rather than being compelled by the forces of law through insolvency. This is often conducted when a company is solvent, meaning that it has enough capability to pay all its debts, and thus is simpler and less messy than compulsory liquidation. It involves the process of settlement, where all liabilities are cleared, returning all available assets to the shareholders, and doing the legal formality necessary for the business to be closed. This is usually resorted to when the company has achieved its objectives, is not facing bankruptcy or liquidation, or it wants to reduce administrative hassle.
It depends on the complexity of the affairs of the company in question. Members' Voluntary Winding Up may take a few months in length without major problems. Creditors' Voluntary Winding Up would most likely take a little longer since it would have to go through its winding-up process relating to paying off outstanding debts and considering claims by creditors.