Hi there!

We don't have too much information on the specifics of this, but just enough that it might help answer your question.

We have a rough estimate that Carpathia confirmed she was headed towards Titanic at about 12:20am. The first lifeboat, boat 7, was launched about 20 minutes later. So we do know that by the time boat launching was underway, Smith knew his closest option (besides the Californian- but that's another debate) was on its way. We can probably safely assume he would have told his 7 officers, but we dont know for sure.

What we can confirm is that junior operator Harold Bride was rescued aboard collapsible B, which just so happened to be the same boat second officer Lightoller was rescued on. Bride informed Lightoller that along with Carpathia, Baltic and Olympic were on their way. Lightoller later drew boats 4 and 12 together, so we can safely assume this news was shared amongst the occupants of those boats at the bare minimum