Is there any service that allows you to check if everyones character or player is loaded in?
You should put this in a localscript for each player:
if not game:IsLoaded() then game.Loaded:Wait() end
game.Loaded is an event for each player that fires whenever a player's game has finished loading. Maybe you can fire a remote event for everytime a player loads? I'm not that good at RemoteEvents and RemoteFunctions so I can't really give you any code.