Well, at this point I would really recomend watching some kind of course or tutorial about replication as this topic is really really wide. Creating anything in networked multiplayer is much more complex than creating the same stuff in singleplayer.
It’s probably better to start with learning resource first than asking for help on forum. It would be faster to learn it in such way.
Client that sends the Server RPC shouldn’t really wait for Server responce. It can fire some of the logic on its own. E.g. pure visual logic (like animations, particles, etc) could be executed right away. This at least creates an ilusion that the game is responsive.