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the performance will commence at 8 pm sharp
Commencement actually is formed with a root word "commence" and a suffix "-ment". There is no prefix.
The ceremony will commence with a short prayer.
The game will commence with the singing of The National Anthem.
Yes, as in "For the evening meal, we plan to commence with a soup course.".
"commence" means "start".
The game will commence in 20 minutes.