When should I switch to part time?

So far my pregnancy has been a rollercoaster. I’m 21 weeks and 1 day today. At first the morning sickness was horrid, eventually it eased up. But now it’s moved on to aches. EVERYWHERE. I was at the hospital today due to my doctor thinking I might have a blood clot (only talked to her over the phone) turns out I have bad pulled muscles in my legs. I work in sales. 40 hours a week. 8 hour shifts. I don’t do heavy lifting but I am required to stand all 8 hours. No breaks. Not even for lunch, I eat on the clock and still have to be standing. It’s just getting to be too much. I’m overly exhausted and my body like I said just aches constantly.

But is it to early to talk about going part time? 🤔