The time-in-grade requirement is a restriction that applies to Federal employees in competitive service General Schedule positions at grades 5 and above. These employees qualify for promotions to higher grades if they have: (1) At least one year of specialized experience equivalent in difficulty to the next lower grade level or (in some cases) the equivalent education; and (2) service of at least 52 weeks at their current grade.
In some cases where Federal employees have education or have gained previous experience outside of the Federal Government they can apply for positions that are open to the general public. These are positions advertised as “WHO MAY BE CONSIDERED: United States Citizens.” You would be considered as an external candidate regardless of your Federal Government status but you will be required to meet the education and/or specialized experience requirements. I suggest you review positions advertised as stated above and review the qualifications requirements for the position. It was not necessary for you to quit your job to be able to move to a position with more promotion potential.
I really hope this information helps.