You can make a new global bool and set it false at round start.
Then when the menu is called, check if bool is false.
If it's false, he hasn't used the menu yet, show the menu and set the bool true.
And you could create the awesome menu inside the clcmd_func along with the menu_go(id) function.
And you shouldn't just copy-paste a tutorial, you should read, understand and try to make it yourself.