The first thing you should do is talk to a tax professional about the tax burden involved with a 401k withdrawal. Are you doing a full-withdrawal? Why? How are old you? <--- Those are all questions that need to be answered. Then speak to a investment advisor about all the options that are available for you. As far as the link of time to get the money, it varies among 401k providers, the most important thing is to make sure you complete their requirements accurately and timely. Any advisor worth their salt will help you, whether they get any of the money or not.
Better get a second opinion on your plan before doing anything.
The most important question, though, is why? Are you unhappy with the 401(k) performance? Is it shrinking instead of growing? Do you feel ignored? If you still work for the company that hosted the 401(k), do they even allow loans or withdrawals? If you don't still work there, perhaps you should roll the 401(k) into an IRA first, to avoid a big tax bill. You need to get professional feedback from a holistic, fiduciary adviser on WHY you want to close out your retirement account to be sure you understand the consequences.