Factory friends doing business in the U.S. market have almost certainly heard of FCC, but many people truly get burned when the goods are already on the ship or when they get delisted by Amazon. FCC Certification governs all electronic products sold in the United States—as long as your product generates RF energy during operation, whether it intentionally emits (such as Bluetooth speakers, Wi-Fi modules, walkie-talkies) or unintentionally emits (such as switching power supplies, LED lights, motors in small appliances), it falls within its jurisdiction. Simply put, consumer products with circuit boards, plugged in or battery-powered, basically cannot escape it.
The easiest thing to get wrong is not "whether it needs to be done," but "doing the wrong type." The FCC divides products into three categories: Verification, DoC, and Certification. Many factories think that casually getting a DoC report is enough to pass, but when the customer asks and it is a wireless product, it must go through Certification (the kind with an FCC ID), and the report submitted directly gets rejected. There is also a high-frequency pitfall: using the wrong standard version. FCC rule updates are not fast, but reports made by factories using old versions of standards are not recognized by customs or platform review, and retesting costs money and delays delivery. In addition, incomplete FCC statements on labels and manuals and incorrect FCC ID formats are also common reasons for rejection—these details look small, but when they block you, it is really stressful.
Now about timelines. For ordinary unintentionally emitting products doing DoC, from sample submission to report issuance, if everything goes smoothly, 1-2 weeks; for those with wireless functions going through Certification, an FCC ID must be applied for, usually 3-4 weeks, and if testing fails and rectification is needed, the time is hard to say. So my advice is: settle the certification plan before the product design is finalized, and do not wait until the molds are already opened to ask "can it pass." When looking for a laboratory, confirm that the other party has FCC-recognized qualifications (such as A2LA or NVLAP authorization), and do not just look at the quotation. There is no "guaranteed pass" in certification, but clear communication in the early stage can save you a lot of trouble later.