Feeling defeated

Hey, all, I am still a student going to a bachelor's in education but I got a job as a substitute while I finish my degree. My first assignment started Wednesday 2/11 and today (2/19) was my fourth day. I feel like I dont know what im doing, I feel defeated, I feel unprepared. My class is only 7 first graders but it felt like wrangling stray cats because their teacher has been out since winter break and they've had other subs cater to them and give in to tantrums. What were your first substitute jobs like? Were you feeling similar? Please tell me im not alone in feeling so lost at the very beginning of my substitute journey.