Caochangmen, Youlan Qintang, Teacher Ma Jie.
Both Nanda and Dongda have Guqin clubs.
Teacher Gui Shimin of Wuyi Lane can go on weekdays. The class fee doesn't seem high, but the teaching is ok. But you have to buy a piano from him, or stare at you without buying it. More than one student has encountered this situation. The piano there is definitely expensive, so grasp it yourself and be mentally prepared. More money is not as good as filial piety, and life will be better in the future, hehe ~
If the class is not too tight now, you can start studying on weekends, go to class once a week and come back to practice. Nanjing is quite hot in summer, so there is no need to concentrate in summer vacation.