My advice as a native English speaker here: In my entire life, I've only seen or heard "till" in the following contexts, given in order of frequency:

1 A cash register (noun)

2 In very poorly constructed resumes

3 In the farming sense (verb)

4 In internet forums alongside poorly written English

5 Shakespeare and other literature from several centuries ago.

So my advice: unless you're a time traveller, use "until".