Just to a little bit to what chin.billy.leung said, "지" is usually used when a specific time is given. So 첫번째 앨범 발매된 후에 is correct but 첫번째 앨범 발매된지 후에 is incorrect. Likewise, 첫번째 앨범 발매된 3년 후에 is incorrect but 처번째 앨범 발매된지 3년 후에 is correct.

첫번째 앨범이 발매된, 3년 후에 This phrase means "since then, 3 years later, after the first album was released,". This means that the first album was released 3 years later since then. Whereas, 첫번째 앨범이 발매된 지 3년 후에 or 첫번째 앨범이 발매된 후(로부터) 3년 후에 or 첫번째 앨범이 발매되고 나서 3년 후에 These clauses mean "3 years later since when the first album was released" The dependent noun 지 refers to a periot of time since when something has happened. This dependent noun is usually used to emphasize the amount of period of time. 첫번째 앨범이 발매된 지(-가) 3년이다. or 첫번째 앨범이 발매되고 나서 3년이 지났다. 3 years passesd by since when the first album was released.

Make sure you have a space between ㄴ and 지 to be grammatically accurate. 지 functions as a virtual noun and it has a particular meaning to describe time interval. This is a set phrase so you just have to learn it by heart. When you describe a period starting from a certain point you will certainly come to usage of that