As far as the IRS is concerned, you can roll funds from a 401k into a personal IRA whenever you want, regardless of employment status. Some 401k administrators will allow for an "in-service withdrawal", which just means you ask them to roll the funds into your own personal IRA. But assuming your intent is to simply roll funds from a 401k to an IRA, then the only limits on doing that are your employer and the 401k administrator.
