A friend of mine keeps using a contraction like this and I keep correcting him by asking "I'll what?". He doesn't get it though, and no matter how much I try to explain it doesn't seem to sink in.
For example, I tried explaining that in most cases you can't use a contraction (more specifically ones that refer to a person(s) like I'll, they'll, he'll and so on) right before who/what/where/when/how/why, that he should use "I will" instead of "I'll" unless he's asking a question; "I'll when?" makes sense, "I'll when it's finished" doesn't.
So, just to clarify, does "I'll when" work when it's not a question?
How can I better explain it to him? I'm having a hard time and I seem to be making a mess of it rather than helping.