As mentioned by Zalcanthrias, the time needed for you to master the program can vary. Dedication, how much time you spend learning and how effecient you are.
For instance, I started with RPG Maker in 2005. I had quite a bit of pauses in between then and now, and I still don't master every aspect of the application.
Let me recommend that you make games to improve. Don't make samples to accomplish this and that. Plan a game that you feel is within your reach and add components as you go. You will improve a lot this way. Usually, one's first game is never completed, or at least not something one's too happy with. If you get stuck with something, ask for help. So basically, you improve on the way, getting answers to simple questions, instead of going for the big bunch from the very beginning.
And yes, simple scripts can be made if you understand the basics, but I reckon that understanding the program to the fullest would be smart before moving onto scripts. This way you can understand all the data files and classes much easier.
I hope stuff works out for you, and if you ever need any help, you know where to post ^_^