Depending on many factors. If you are healthy and in a safe environment and depending on what activities you do you could work right up to delivery day.

Firstly - not all men want penetration, and you might not always offer that. *Some women don't offer PIV at all (I don't) (PIV = penis in vagina.

And some have fetishes about pregnant women which you could satisfy and charge more for.

You can also consider being breastfeeding and working after pregnancy for guys with the lactation fetish - milkmaid - again can be fun and lucrative if you want to do those things.

If you want only to work until the baby shows then you might need to stop anywhere between about 16 -20 weeks.

Good luck with the pregnancy and the work and every thing.