It depends on your body fat percentage. Everyone has abdominal muscles, but it's just obvious. If you are thin, you will have obvious abdominal muscles after 2 weeks. If you have more fat, you have to lose fat first, and the length of time is not necessarily. I suggest you watch the video "gut", which is quite effective. The most important thing is persistence, no matter what, we must persist. You don't need to practice until your muscles ache every day, but you must exercise every day! Wish you success!