How can I so better?

Hey guys! So l've been a busser at this restaurant for over a year (Since I was 16, I am 18 now). I just started getting serving shifts in April-ish and only once a week or two. I've had some rough days and needed help but I've gotten my groove better, but tonight was a different story. I came in and there was a 30 top expected at 6pm (I came at 5pm). There was already about a 9 top that came in, and then a 3 top, another 9 top, the 30 top came in but only 15 came, an 8 top came in, a two top, and a three top. This was basically all at once as people kept trickling in. This was a Wednesday and we never have bussers on these days, only Fridays and Saturdays. However, we had two big events going on, and the 30 top has been a reservation and was not prepared when I got there and I didn't have time to set it up with everything. Sorry for the long story, just want to ask what the best way is to deal with this again. I tried my hardest and I'm hard on myself, but I want to get better! I got help later on since they had to call in someone, but I was alone in the restaurant for the first part. Was this my error, a management error, or just a coincidence?