Don’t know where to post this! Question about puberty in boys!

If you’re a veteran mom(meaning you are a parent to an older child/teen/adult) and you have a son, when did he start puberty? What were the first signs? My son will be 9 this year and I haven’t noticed anything but a growth spurt but I have a feeling puberty will start “soon”. I grew up with all girls, so this will be a first for me but I want to be prepared. His father had a full on beard at 15 so I’m thinking my son will also be an early bloomer. We have open communication and we’ve had talks about puberty and whatnot but I just want to know if there are signs and symptoms that signify that puberty is upon us, otherwise I guess I just wait for his first pimple? 😂 thanks!