Show loading image on check box checked - Nintex form

Hello there,

I have a nintex form and a  choice field with value "Yes"

When i check the check box, on check change - i am executing some code which is taking some 2 mins time. So i want to enable a label with message before start of executing the code and hide the label after execution of code completes.

But the label  is shown and hidden only completion of execution of the code.

Can anyone help me to implement something like this. 

Thanks in advance,

Usha