Let me tell you this: There is never a wrong time to start leaning. So, when you have time I highly recommend that you download the module "TKInter". You can install it through pip. This module will help you in developing basic GUI's.

But wait! If you want to develop apps on android or iOS, python won't help. For android, you need to learn Kotlin or Java, for iOS you need to learn Swift. But don't worry, with python you can make apps for windows. When you learn how to make a good GUI and eventually make a python app, you can easily convert it into a .exe file for windows compatibility. Learn how to convert it here https://www.geeksforgeeks.org/convert-python-script-to-exe-file/