Theres a thing called tasks which run every tick u can customize them to many things like repeat a message for a specified amount of time or what ever to make a delay simply make a task which when a player runs the said command it starts a task. then if a player says that command while the task is running in chat it will cancel the event look up more about tasks on the forums or pmmp in general before attempting making a task.
or simply store the date when they run the command and everytime they run it compare the stored date with the current date.
How is making a repeating task per command player that will lag the entire the server easier than checking if an interval is higher than the desired amount of time? PHP: $storedTime = time();if(time() - $storedTime >= 5 * 60) { echo "5 minutes have passed.";} else { echo "5 minutes have NOT passed yet.";}