IEEE MMSP 2022 timeline has been confirmed:

Special Session proposal submission：July 10, 2022
Regular and Special Session paper submission: July 3, 2022
Notification of Special Session paper acceptance: August 3 2022
Camera-ready Special Session paper submission: August 10, 2022
Notification of paper acceptance: August 3, 2022
Demo paper submission: August 13,2022
Camera-ready paper submission: August 13,2022
Presentation and video submission (see Instructions for Authors): September 15,2022
IEEE MMSP 2022 virtual conference: September 26-28,2022

You can find the full list of important dates here.