I'd recommend telling your employer sooner rather than later, even at 8 weeks. From a legal standpoint, you're generally protected from discrimination once you disclose, and it's harder for them to claim they didn't know if complications arise later. I'd suggest scheduling a private meeting with your direct manager or HR - don't do it casually or in writing as your first notification. Keep it professional and straightforward: "I wanted to let you know that I'm pregnant and expecting in [month]. I'm committed to my role and we can discuss any accommodations or timeline adjustments that make sense."
The key is framing this as information they need, not a problem. Have a rough idea of when you plan to take leave, but you don't need all the details worked out yet. Many employers actually appreciate the heads-up because it gives them time to plan coverage. If you're in the US, familiarize yourself with FMLA and your state's pregnancy leave laws before the conversation - knowing your rights takes pressure off and keeps things grounded. It's worth noting that most employers are used to this and handle it professionally, despite how scary it feels beforehand.
As for timing, if you're waiting because of the first trimester miscarriage risk, I get it, but that's a personal choice. Legally and practically though, your employer needs to know for liability reasons and workplace safety. Once you tell them, most people find the dread was worse than the actual conversation. Just keep it factual, professional, and don't oversell or over-apologize for being pregnant - you're not doing anything wrong.