Before printing you have to convert to cmyk. But it is something that the printer has to do since the cmyk profile is not a standard, it is a conversion of the rgb color space of the monitors to the most accurate approximation that the ink mixture can perform. As each manufacturer has different inks and each substrate (paper, vinyl, canvas ..) has a different white background, it is up to the printer to properly calibrate the output profile cmyk for each printable substrate and each machine with its corresponding set of inks .
It is something that is always misunderstood, even nicked had a photoshop action to convert to cmyk !! And I say … what cyan? What magenta? The roland paints? Epson ? Eco-dyes, dye, latex ?? As you will realize is something impossible to do standard, even two machines of the same model and the same manufacturer print different.
What is important is that you properly calibrate your monitor, and that the monitor is the best possible. If you have a conventional Srgb monitor, work the photo in the Srgb color space and send it to the printer in that color space. If you work on a wide gamut monitor adobe RGB works with that color space and sends it to the printer with the (provided the printer has a wide gamut monitor, you should) The most important thing in the calibration of the monitor is the brightness, The monitors generally have a very high brightness. To work if you want to output print the brightness of the monitor should be around 140cd / m2 to about 160cd / m2.
If you do not have a calibrator or a suitable monitor, it is best to work the photo in SRGB and take it personally to the printer to teach you on your monitor well calibrated and after converting the image to the corresponding cmyk color space and thus, insitu , You can appreciate the most accurate approximation to how it would look, in case you need to raise the brightness or contrast of the photo to leave the result to your liking.