You have some rights without registering. In the United States, using a mark in commerce creates common law rights in the geographic area where you operate, which can be enough for a business serving one city and intending to stay there. What registration adds is a presumption of ownership nationwide, the ability to use the federal symbol, a stronger position in any dispute, and a public record that causes other businesses to find you before they adopt something similar.
The situations where registration is worth the cost are recognisable. You are building something you intend to expand beyond one market. Your name is distinctive rather than descriptive and therefore worth protecting. You sell online where geography does not limit your exposure. Or somebody else operating in a similar space has a similar name and you would rather establish priority than discover it later.
The situations where it is premature are equally recognisable. A business that may rename within a year. A name that is descriptive of what you sell, which is difficult to register and weak even when granted. Or a local service business with no expansion plans, where common law rights in your area cover the realistic risk.
Search before you commit to the name rather than before you register it, which is the sequencing most businesses get wrong. Check the federal database, your state registry, and ordinary search results for anybody using something similar in a related field. Discovering a conflict after printing signage, registering a domain, and building a year of search visibility is the expensive version of this, and the search itself is free.
The process can be done yourself and frequently is, and it is also the kind of thing where a mistake is discovered eighteen months later when an examiner refuses the application. An attorney who does this routinely will conduct a proper clearance search and identify problems the free databases will not surface. This is general information rather than legal advice, and a name you intend to build a business around is worth an hour of professional time before you commit to it.