In this section the following words have the meanings indicated. “Eligible child” means a child: Whose parent or guardian enrolls the child in a public prekindergarten program; and Who is 4 years old on September 1 of the school year in which the parent or legal guardian enrolls the child in a public prekindergarten program. “Eligible county board” means a county board that makes a full–day public prekindergarten program available for eligible children. “State share of the per pupil foundation amount” means the quotient of the State share of the foundation program for a county divided by the full–time equivalent enrollment of the county. For each of fiscal years 2018 through 2022, the State shall provide a supplemental prekindergarten grant to an eligible county board that equals the percentage of the State share of the per pupil foundation amount multiplied by the number of full–time equivalent eligible children enrolled in a public full–day prekindergarten program on September 30 of the previous school year: For fiscal year 2018, 50%; For fiscal year 2019, 75%; For fiscal year 2020, 100%; and For each of fiscal years 2021 and 2022, 100%. The State shall distribute the supplemental prekindergarten grant at the same time the State distributes funds to county boards under this subtitle.