Already

google

ref

Middle English: from all (as an adverb) + ready; already (sense 2) is influenced by Yiddish use.

wiktionary

ref

From Middle English alredy, alredi, equivalent to al- +‎ ready. Compare Dutch alreeds(“already”), Afrikaans alreeds(“already”), Middle Low German alreide, alreids(“already”), Danish allerede(“already”), Swedish allaredan(“already”), Norwegian Nynorsk allereie(“already”). More at all, ready.

Semantic loan from Yiddish שוין‎ (shoyn). 

etymonline

ref

already (adv.)

c. 1300, "in a state of readiness" (an adjectival sense, now obsolete), literally "fully ready, quite prepared," a contraction of all + ready (adj.). Compare Norwegian, Danish allerede "already." As an adverb, "by this time, previous to some specified time," late 14c. Colloquial use in U.S. as a terminal emphatic (as in enough, already!) is attested from 1903, translating Yiddish shoyn, which is used in same sense. The pattern also is attested in Pennsylvania German and in South African.