Sending your man booty pics!?

So I have sent him photos before but I don't really know how to initiate it, do I text him and start a conversation first? I want to send them to him while he's at work but I'm not sure if it's the right time. Last time I did he was like "ohhhh my god, yummmmmm 😍 thanks baby 😍 💓💙" so I'm assuming he likes it. I'm real bad at sexting but I just want to send him some on occasion to make his day better. Any advice on how to initiate it or should I just send then with no text? 😂 help