Is it illegal to send this via text?

If I sent a pic of me in short shorts(not booty shorts though) and a tank top that's shortish but still below me bellybutton and the top of my undies showing. Would that be illegal? Were both under. 18 but he's gonna turn 18 this yr...if it's still on his phone when he's 18 will he get in the same about of trouble even though he received it when he was 17? Thanks