It totally depends on you. You can master it in 6 months or in a year. The only thing is, how you prepare for it. What I would suggest to you is that just search for resources and start learning. Who knows, you learn much faster than you ever imagined! I can suggest some of the resources that will help you immensely. The first would be the GCP Training Course offered by Intellipaat. You can also read this much informative GCP blog. I am also sharing a video tutorial, which can help you learn GCP in a shorter time span: