We have first communion parties for our kids and invite family and close friends. The family and friends may not be practicing Catholics themselves but they love our child and share in our joy. I wouldn't invite casual non-religious friends.

We had first communion parties growing up (in the 80s) but we had a large extended family and all the aunts, uncles, cousins, maybe some family friends/neighbors would come. There would typically be about 50 people. It would be at the house, with catered hot dishes and salads and a cake. Only the first communicant, siblings, parents and godparents would attend the first communion in the church.

For my own children, we live far from extended family. For my oldest child the grandparents/great grandparents came down to celebrate, but they have not been able to do that with the other kids (We have many children, each 2 years apart).
So for each child, we have just one out to dinner at the restaurant of the first communicant's choice, then home for cake.

Where I come from, yes, this is common. It's not typically a huge invite your friends kind of thing. It's a small family/godparents/closest friends kind of thing. There's lunch and a cake, and kids generally get a few presents from their parents, grandparents and godparents. Usually religious items and money; the money is often used to open the child's first savings account.

We have them in my very Catholic neighborhood. They can be as fancy or as simple as you like. Most aren't huge, simply becuase everyone else in the class is having a competing party at the exact same time!

We had first Communion parties when I grew up in Pittsburgh a million years ago. I have not heard of them since I've been in Washington.

My parents came up from Florida and my sister lives nearby. We invited the godparents as well as a few families with whom we're friendly with at church. It was a simple lunch after mass. And of course there was cake.

You don't have to have a party. You can go out for a really nice lunch with your immediate family and celebrate with your son. Even if just the grandparents came, that would be perfectly fine.

Sorry, I'm kind of dense on these things, most of my friends are Jewish, and my oldest is a year behind in CCD because we weren't quite on the ball. He's making his first communion this year and I am wondering if people typically have parties for these events. Growing up, this was a really big deal, and I'll invite family but since they are all a plane ride away, I'm not sure who if any will come. Would it be weird to invite friends who are not Christian to a party at our house after the Mass? What do most families in the DC area do for this milestone? Thanks!