As my son got older, if I hadn't told him I would guilty as fuck lying to him all the time. Making up reasons why I couldn't answer the phone, or what project I was working on, etc. He would also have come to realise that's it's really not usual to go out at 9am and come back at 7pm with £600 in cash.
If he'd found out 10 years down the line that I'd been lying to him for the last 15 years, I think he would have felt very very betrayed. Honesty has always been an important component of our relationship. (He has some long term MH issues with being abandoned by his birth mum, and his birth dad was a pathological liar.)
OP I'm glad it went well. Your son may need reassurance in the future. I'd would suggest you don't ever say anything graphic or ever talk about the negative side of things. I talk about sex work politics with my son a lot. I also tell him about rewarding bookings (about the emotional side, not the sex side!), like disabled clients, widowers, guys who have just been through a really hard time and wanted to talk, etc. I also talk to him about visiting new cities and seeing lovely architecture, going to art galleries, etc.