As a Changsha person, this is actually a "hidden rule". Give you a red envelope. After all, people helped you get married. The exact amount depends on how you behave. 1000 is quite appropriate, but you should note that Changsha people like to be polite, so they will be influenced by you if you push them from one place to another. Of course, people really don't want to push, people will think you are. Any time is fine, but do you think it is "tasteful" to give it in front of everyone at the wedding?