till |til|preposition & conjunctionless formal way of saying until .ORIGIN Old English til, of Germanic origin; related toOld Norse til ‘to.’USAGE In most contexts, till and until have the same meaning and are interchangeable. The main difference is that till is generally considered to be more informal than until. Until occurs much morefrequently than till in writing. In addition, until tends to be the natural choice at the beginning of a sentence: : until very recently, there was still a chance of rescuing the situation. Interestingly, while it is commonlyassumed that till is an abbreviated form of until (the spellings 'till and 'til reflect this), till is in fact the earlier form. Until appears to have been formed by the addition of Old Norse und (‘as far as’) several hundred years after the date of the first records for till.
I have a tendency to use "till" in writing and speech more often. Maybe it's a European thing, I don't know. But I've had crit partners and editors both "correct" them in my manuscripts before.