Except as provided under subsection (b) of this section, a county board shall ensure that: Beginning in the 2024–2025 school year, prekindergarten slots provided by eligible private providers shall account for at least 10% of the total prekindergarten slots provided by eligible prekindergarten providers in each county; The proportion of eligible private provider prekindergarten slots in each county increases by 10 percentage points every school year, until, in the 2028–2029 school year, eligible private provider prekindergarten slots account for at least 50% of eligible prekindergarten provider prekindergarten slots in each county; and In each year after the 2028–2029 school year, the proportion of eligible private provider prekindergarten slots in each county shall continue to constitute at least 50% of eligible prekindergarten provider prekindergarten slots in each county. The Department shall issue a waiver from the requirements of this section to a county board if: All families in the county who desire to enroll their eligible children with eligible prekindergarten providers are able to do so; or After reasonable cross–jurisdictional or regional efforts, there are too few eligible private providers to meet the minimum requirements of this section; and The county board demonstrates to the Department that it has made a good faith effort to fully embrace the mixed delivery system, including by adopting a memorandum of understanding in accordance with § 7–1A–05 of this subtitle. The Department may exclude by annual waiver Tier I children who are 3 years old in a county from the calculation under subsection (a) of this section until the 2031–2032 school year. The Department may exclude by annual waiver Tier I children who are 4 years old in a county from the calculation under subsection (a) of this section until the 2028–2029 school year. The Department shall establish waiver application procedures to carry out the provisions of this subsection.