(verb) to start or begin.
"The trial commenced with the prosecutor’s opening statement."
initiate: "The plaintiff initiated proceedings against the defendant by filing suit in district court."
conclude: "The meeting concluded with a question and answer session."
cease: "The court ordered to the defendant to cease harassing the claimant."
terminate: "When its sole buyer terminated the contract, the seller decided to no longer manufacture the widgets."
commence litigation- file a lawsuit "If we do not receive a reply within 10 days, we will have no choice but to commence litigation in a court of general jurisdiction."
commencing on - refers to the date on which something commences. "We will monitor your usage commencing on 15 May and notify you monthly if we notice any irregularities."
Related words and concepts
enter into force (verb) - to become legally valid. "When the insurance policy entered into force on 15 May 2004, the manufacturer was able to begin production."
Translegal Digest (http://www.translegal.com/digest/modules/smartnews/item.php?itemid=2)