The rule does not apply to an IRA withdrawal which remains at age 59 1/2 unless the withdrawal is eligible for an exception to the 10% early withdrawal penalty. See IRS Tax Topic - https://www.irs.gov/taxtopics/tc557
The IRS Rule of 55 allows an employee who is laid off, fired, or who quits a job between the ages of 55 and 59 1/2 to pull money out of his 401(k) or 403(b) plan without penalty. This applies to workers who leave their jobs anytime during or after the year of their 55th birthdays.
If you are eligible you can withdraw funds from the 401(k) or 403(b) plan without the 10% early withdrawal penalty as long as withdrawal occurs during or after the year of your 55th birthday.