I am very much excited but at the same time very scared. My first job working for what I am studying. So Monday(18-June-2018) I am starting work at this small company as a Java Junior developer. I'd like to know from those who are in the industry already, how was the transition from school to actually working for a company?
I'd also really appreciate some bit of advice from everyone.

You will be fine. Most people learn everything on the job

@otavio I hope so :-)

Depends on the place you work and the kind of stack. I maintain Java programs at work because I was an Android developer before. Started with Java years ago and the company decided to have me doing Android apps. At work I maintain web Java apps and php apps and had to learn some server admin stuff that i had not done before as well as some networking. As long as you show enthusiasm and competence you will be fine :)