Personnally, I rather say "ça va commencer quand?" when I speak (I think it sounds more natural than "quand ça va commencer?". If you want to speak more formally, you can also replace "ça" by its corresponding noun ("le cours", "la conférence",...) and say "quand va commencer le cours/la conférence?".
Hope that helps!
Hi,
I do not agree.
To me, "quand va commencer le cours" sounds awkward, because you cannot invert the subject when it is not a personal pronoun.
You may hear "quand ça va commencer" or "quand le cours va commencer", and I think they are informal.
To me, the form "Quand va commencer le cours" sounds more formal because of the inversion, but shows a laxer syntax, because of the strange inversion.
I think the correct way to ask such a question in speech, with a correct level of formality, can be done by putting "quand" in the end :
"Ça va commencer quand?" or "Le cours va commencer quand?". They sound very natural in speech, and not so informal.
In a text, however, The inversion is highly required, and in that case, you put the "quand" back in the beginning, and make the inversion with a fake "il" :
"Quand cela va-t-il commencer?" or "Quand le cours va-t-il commencer?".
The latter two are ok only if you are writing, because in speech, they are somewhat heavy.