Goku does not have a canonical birthday, fam. It's entirely fan-invented. Which is fine, to be clear, but don't beat yourself up or stress too much if you think you missed the day. Celebrate it whenever you like.
(I personally prefer to think of it as the day DB premiered. lol)
BUT, if you choose to celebrate it today, have fun!
The scene in Dragonball Super when Goku reenacts the last time he saw his Grandpa was a scene that took me by surprise when I recognised what it was he was doing.
Just goes to show how much love and attention to detail Toei Animation put into the series.
Dragonball is so well loved, even 40+ years later, and I'm sure it'll continue to be for many more generations.
Obviously I couldn't include all of them, so I tried my best to select the ones I thought were the most popular. If there's another character you feel should be on the list, feel free to mention them in the notes!