An altered version of Sbare's Gateway timer. (https://wago.io/cdv7nD3fy)
It now uses custom sounds. Incl. a proper countdown to use the gate, and a Verbal warning to set the gate to focus.
This altered version needs Ascu's SharedMedia addon to work.
Get it on wowup etc, or here :
https://www.curseforge.com/wow/addons/ascu-sharedmedia-bigwigs-countdown/files