How to do loading screen in tkinter?

Question

I have these few lines of code here which have converted it to exe file using pyinstaller but want to add loading screen to it. So that it will alert the user the application is loading to prevent the user from clicking on again for it to open several times.

I found these links link1 link2 but the answers there doesn't come with demo to achieve that.

import tkinter as tk

root = tk.Tk()
root.geometry("400x400")

b = tk.Button(root, text="trying to do loading screen", command=None)
b.place(x=200, y=100)

root.mainloop()