Until, till, and 'til are all used to indicate the time when a particular situation or period ends, or when something will happen. Until and till are both standard (but, perhaps surprisingly, till is the older of the two). 'Til, with one L, is an informal and poetic shortening of until. 'Till, with an additional L, is rarely used today, and should be avoided.

https://www.merriam-webster.com/grammar/should-you-use-until-or-till-or-til

You understood what he meant. Ergo, he was correct.

Language is just a means of conveying your thoughts into someone else’s head. Grammar is a set of guidelines to ease that process. So if you picked up what he was putting down, his sentence was valid.

Na mean?