we have had several sleepovers. The boys have had up to 10 spend the night before and did fine. Girls have more fights, arguments, and drama. Always make sure you have even numbers because someone feels left out with odd numbers and never do 3 because that triangle never works out. Usually it's your kid feeling pulled in the middle making choices they don't want to make with the triangle situation..especially with girls. I have helped with an annual girls sleepover at church for the past 7 years and we have had up to 75 girls attend. With groups that big we have to entertain and keep them constantly busy or major DRAMA happens. Our goal is to wear them out until midnight and then put in a movie and hope they are asleep by 2 am when the movie is over. Most of them get up by 7 and we have breakfast at 7:30, pack up and they are ready to leave by 9 so we don't really plan activities for the next morning as it takes them a while to get everything packed.
I let them stay up as long as they want, usually they fall asleep by 3 or 4 am. I usually go to bed at 2 or 3 am and tell them at that point they have to lay down and watch a movie and can talk quietly but don't let them stay up running all over the house once I decide to go to bed.
I always dream that they will sleep in since I let them stay up late but just about every sleepover someone will wake up at 6 or 7 am so then I get up and usually turn on cartoons or put in a movie with the volume on as low as possible and tell the ones that are awake to watch a movie and not wake up the other kids. Most of the time that works for about 1/2 hour or an hour.
I don't entertain them much with the sleepovers we have at home unless we all want to play a board game but most of the time they play video games or watch movies.
We usually have pizza to eat in the evening when they seem hungry and I usually make pancakes for breakfast.
I usually have them start at 7:00 PM and end at 9 or 10 am. If you have them picked up too early then you are usually rushing around all morning to have them ready when the parents come to pick them up and that can be very overwhelming and wear you out especially if you didn't much sleep.
I am easy going and kids noise doesn't bother me at all and have a lot of patience so sleepovers don't bother me.
You mentioned being anxious so you probably wouldn't want to start with a big group and start with 1 spending the night then try another one with 3 friends+1 (your kid) and see how well that goes.
Would recommend the kids be past Kindergarten age for sleepovers. They tend to get homesick and whine more when that young.