Your next assignment, before you get there.
Orders move your housing allowance, and the new rate is published before you report. This prices that one change from the DoD table: what you draw now, what the new duty ZIP pays, and the difference each month.
One number, on purpose. Your base pay and the deductions on your LES are not part of this answer, so nothing here is a forecast of your whole check.
Rates come from the published DoD/DTMO table for the report year. When the new rate cannot be sourced, or you have not settled where you will live, the figure is held rather than guessed. Educational and directional only, not financial advice. More military tools.