If you're direct-sowing seeds outside, I think it's too cold now for anything. The top layer of soil may be thawed, but down where the roots are going it's still frozen. Besides, working cold, soggy soil destroys the structure and disturbs beneficial microorganisms that are hibernating right now. If you're starting seeds indoors, depending on what you're starting, it's probably not too soon.
One more thought on the outdoor bed. Depending on how it's sited, you may be able to plant earlier or have to wait a little longer to plant. I.e.: if the bed is facing south or west sun exposure, or full sun, or is raised, it can be planted earlier. If it's at the bottom of a slope, or in partial shade, or facing only eastern sun, then later, and depending on the amount of sun it gets during the day, you may be limited as to what will give good yield there.