Not that it's something you're going to need right now. What's more, we don't even know if you'll ever need it. But just as you can know when any of your email accounts was created; what was your last purchase in app stores, it is also possible know when you created your Apple ID.
Although you can do the same through your iOS device, on macOS you must turn to iTunes. What's more, you will have to go to your purchase history to be able to know the creation date of your Apple ID. As we tell you: it is not something that you currently need, but it is possible that in the future this information will help you to restore some of your parameters.
Well, that said. Open iTunes and we go to the menu bar. There you will have to select the "Account" option. And then we are interested in the option «See my account». When pressed, it will ask us to authenticate ourselves and enter our Apple account password. Once this is done we will have access to all our data: personal data; Bank data; how many devices are linked to iCloud; the active subscriptions we have; the possibility of adding a balance to our account to be able to make purchases without using credit cards and, what interests us, "Shopping history".
When entering this option we will have a list of the most recent purchases we have made with our Apple ID; that is, either through the Mac App Store or the App Store. However, if you look closely, the period that is being displayed is the one that refers to the last 90 days. Well, it is in this section where we must click again.
A new drop-down is presented to us and the years in which our Apple account has been active will appear. Click on the most distant year - the first at the end. Will be then when you can select the month again and you will be able to check since when our Apple ID is active. In my specific case, I have it active since July 2007.
Just one point. It is not entirely correct that the date indicated is the date when the Apple ID was created. It is good to get an approximate idea, but in my case and surely in many other users, it does not correspond.
My first Apple device was a second generation iPod nano from 2006, which was my first experience with iTunes and the creation of the Apple ID. My first purchase using my ID was in 2009 when I bought the iPhone 3G and already bought apps.
For being a little more precise with the dates.