People often ask which is the correct synonym of until: till, ’til, or ’till?
Many assume that till is an abbreviated form of until. Actually, it is a distinctive word that existed in English at least a century before until, both as a preposition meaning “to” and a conjunction meaning “until.” It has seen continuous use in English since the 12th century and is a perfectly legitimate synonym of until.
’Til and ’till are much newer words, having appeared in the language only in the 19th and 20th centuries, respectively. Both are variant spellings, either of until or of till. Writers of usage guides have roundly condemned ’till as a barbarism (apparently because it seems to have added a superfluous l to the end of until). ’Til, for its part, has been deemed inappropriate in formal writing.
To sum up: until and till can be used freely and interchangeably, but you will probably want to avoid ’till and use ’til advisedly.