What is the proper boat launch etiquette?

Check in with the facility that you will be boating at to check their rules and regulations. Also observing a few boats launching may give you a better idea of how to do this process.
Prepare the boat away from the ramp to avoid blocking other vehicles

When preparing a vessel for a maiden voyage, have it on the ramp or in a lift alongside the dock. If you wish to " christen " the craft , have the designated person stand at the bow end with a bottle of champagne [ might as well use cheap one, nobody is going to drink it ] , raise the bottle aloft , then say as follows " I christen thee the [ EX ] Stella Maris . Godspeed and safe passage to her and all who sail on her ." . Then break the bottle over the bow[ careful of flying glass and NOT to damage the new vessel ] The drink a toast with the beverage of your choice.