“Before what?” you ask. Before you actually launch something. Before you sell. Before you are even ready.
If you are going to start something new – the minute you decide that you are going to do it, is the right time to start marketing – do not make the mistake of waiting with your marketing until everything else is finished and ready for launch.
Sometimes it starts even earlier – I know people who start their marketing before they ever decide to do something. Just in case.