setting for printing in Fresco

Working in CYMK from the beginning (early-binding) *is* the old way. Modern workflows have shifted to keeping the file in RGB and doing the conversion late in the pipe, when rendering the plates (late-binding). Just check how PDF-X versions evolved and you'll see this is true.
Working directly in CMYK may seem simpler, but it has a serious disadvantage: Your work is tied to an specific CMYK colorspace. So, if you have to move to a different print provider or paper stock, your CMYK separation won't produce the correct results anymore. This is crucial and most of the people advocating for CMYK seem to miss the point: There is no universal CMYK. Each printer and paper stock has its own CMYK colorspace.
When you keep it RGB, you keep more color latitude and that means that every time the CMYK conversion is done (by your print provider or by yourself when you're prparing your artwork for print) it's done from a rich source.

If you created your artwork in RGB, making sure that your palette more or less falls in the printable colors gamut, then you can be 100% sure that your artwork will print ok almost everywhere.
If you created your artwork in CMYK, your file will be only good for specific printing conditions, and might produce bad results when moving to different printing conditions (SWOP vs. FOGRA shops, coated vs. uncoated papers, even different brands of papers, etc.).

That being said, chosing early or late binding is up to you. Early binding is not wrong, you can still use it, but you MUST know exactly where your artwork will be printed and how, and you have to know that if you switch providers you'll have to convert it to a different CMYK colorspace anyway. And that will have a worse impact on your artwork than going from RGB to the proper CMYK once.

Of course, because of the trend of using RGB all the way during the creative process some programs like Fresco won't offer that choice, so you have to treat your images created in Fresco as if they were digital photos of your artwork. I make this analogy because it is exactly what you have to do when you create physical media and take a photo of it or scan it. And not having CMYK there never stopped creators from doing stuff for print before.