There isn't a usual time embargo. As has been said, no-one has to read this thread... but to correct one point made, everyone knows the closing date because it's printed in the online pdf as well as in the mag.
I'm also glad you're sticking with it and learning, and at least you're not asking us to answer every clue like some previous would-be solvers!
I guess we'd normally expect questions to start appearing after two or three days, but that's not a hard and fast rule. In fact there are no rules.
But don't ever ask for help with a clue in the Listener crossword (in fact, my advice would be don't ever attempt the Listener crossword except under medical supervision, but that's by the by).
The wrath of the righteous will then descend on you quicker than somewhat, because such knowledge is known only to the ancients and cannot possibly be revealed.