I'm going to miss my first day of high school

I'm going into my freshmen year of high school I and found out today that I'm going to miss the first day and I'm really freaking out. in august I'm going to Brazil to visit my family and I was wondering when we were leaving and coming back and I'll be missing summer camp (its also my last year and I've been going there since the summer before 6th grade) and freshmen orientation and my first day and before I was feeling very prepared and really excited mostly because I'm coming from a much smaller k-8 school and I've been in the same class for 5 years so its a really big change for me. right now I'm just feeling a lot of FOMO and before I was finding comfort in it being a new experience for everyone and that it would help me with making new friends because I'm a pretty quiet shy person and I only have a few friends that I consistently talk to. so overall I'm just really worried about missing out and just feeling  alone and I'm just going to be constantly worrying over it for like the next two months and I want to talk about it with someone but I don't definitely going to cry and its going to turn into a huge long talk long and I'm just not sure how to make the situation any better and I just feel so worried and unprepared.