Shabbat poses a problem because the family then has to have accommodations for the guests available, or turn a blind eye to those driving. One solution for that is to have a big party that night or the following Sunday. Then you can also have a band. And thus was born all the wedding like bar mitzvahs we've seen.
Another is to have it on a weekday - a Monday or a Thursday or a New Moon. But Mondays and Thursdays are inconvenient. People have to go to work or to school and morning services are very early. On the other hand, it teaches the boy that it's not just a party. It's part of life. And you can have a bagel and fish spread, which is lots cheaper. No band, though.
This is the best of both worlds - it's a day most people have off of work and school. Not all, mind you. In my neighborhood, school started *yesterday*. On Sunday. But for the most part, it makes sense. They got to have a lot of people at the service, they got to have a nice brunch with a hot dairy buffet, and a keyboardist so there was music. The young man made a very impressive speech on the tractate of Talmud he and his father finished, and there were other speeches as well, and we could hear it because they could use a microphone. They had a cake with candles for a three year old who had her birthday that day. They had a great grandmother of 104 who loved being wheeled into the center of the women's dance (well, shuffle - t here wasn't much room) circle. They had a fiftieth anniversary to celebrate. It all worked out beautifully.
The father of the bar mitzvah boy takes a Talmud class with Jonathan. We rode there with another member of the class...and rode back with the wife of the teacher, and we all sat at the same table. Was nice. The actual teacher showed up for a few minutes, but he was working today. As I said, school started yesterday. Lovely people, all of them.
We got home, I took off the suit and put on more comfortable clothing. And spent the rest of the day watching a bunch of Navy men try to be Seals, while I did cross stitch. Was fun.