It all depends on your skill level. Some people can learn basic cooking techniques in as little as a week. Others may take months or years to master the basics of cooking.
The amount of time needed to learn to cook varies considerably based on the person. One example is that someone who has never tried cooking before would likely take more time to learn than someone who cooks often. You may also need more experience with certain types of cooking than others. Baking is more difficult than frying.
If you want to learn how quickly you can cook, you should focus on learning a specific technique. You can then move on to the next technique once you have mastered it. You shouldn't stress about how long it takes to learn how cook. Just keep practicing and enjoy the process.