According to my experience, Tian’s calligraphy is based on the European style, which is relatively difficult and not easy to learn. You can practice it later when you have a little foundation. Beginners can start with Pang Zhonghua's, which is easier to see results. Don't think that Pang Zhonghua's calligraphy is not good-looking. His calligraphy has the flavor of facial expressions and is easy to get started with. After you get started, you can learn other things.
If you keep writing every day, you will definitely get results in two or three months. It is best not to change copybooks frequently in the beginning.