when can I get the new software update?

On an iPhone at Settings > General > Software Update.

Also see: Update your iPhone or iPad - Apple Support

There is almost always a "new" update that some user is asking about. Not sure which one that you are referred to.

Have you tapped Settings > General > Software Update to see if new software is available?

Start here: Update your iPhone or iPad - Apple Support. Depends on what phone you have as to what current iOS version you will get.