noun, adverb
Formal, somewhat literary expression for 'from this point forward'. Often used in official announcements, legal documents, or solemn declarations. In everyday speech, これから or 今後 are more common.
自今、この規則を厳守すること。
From now on, this rule must be strictly observed.
自今の行動に注意されたい。
Please be mindful of your conduct hereafter.
Compound of 自 (from) and 今 (now). The exact historical derivation is uncertain, but it has been used in formal written Japanese to mean 'from this moment onward'.