Commencing with the 2003–04 fiscal year, for the purposes of allocating the advance apportionment for the current fiscal year, the Superintendent of Public Instruction shall on or before July 20th of each year certify to the Controller the amounts estimated to be apportioned to each effective school district for the current fiscal year on the basis of the report of the districts for the second principal apportionment of the preceding fiscal year, the amounts estimated to be apportioned to each county school tuition fund and to each county school service fund for schools and classes to be maintained by the county superintendent of schools during the current fiscal year on the basis of reports provided by the county superintendent of schools, and the amounts estimated by the Superintendent of Public Instruction to be apportioned to the county school service fund during the current fiscal year under subdivisions (a) and (b) of Section 14054.