OK. The Canon MX410 is a general home/office inkjet printer, so the color profile necessary to get a precise print simulation on screen probably isn’t available. You can still get a rather rough approximation of how it will print by choosing View > Proof Setup > Working CMYK. You can toggle that on and off by choosing View > Proof Colors.
It will be only a rough approximation because the CMYK profiles installed with Photoshop represents printing press inks, not the inks in home/office inkjet printers. But it should get you close enough to know what to expect. Because you are selling the invitations online, they will be printed by others, on other printers you can’t know about, right? In that case, how your Canon printer reproduces the colors is less important than how the colors reproduce in CMYK generally, so simulating print colors on screen through a generic CMYK profile is acceptable in this specific case.
Simulating on screen is called soft-proofing. It works best when the display has been color-calibrated and/or profiled.
However — very important — doing this does not create a screen-to-printer color match on its own. That’s usually impossible for the reasons I stated above: If your document has any colors that are outside the range that the printer can reproduce, such as a very bright blue or neon green, there is no way to print that color. What soft-proofing does is set your expectations about what colors the printer is actually capable of. With View > Proof Setup enabled, you can continue to edit the colors while seeing approximately how they will print. Or, if you don’t think there’s much you can do, you can simply go ahead and print, knowing that it will look somewhat like it does when Proof Setup is on.
This is nothing new, and not specifically the fault of an “old printer.” Even the newest and most expensive CMYK printers can’t reproduce all the RGB colors you see on screen. Working with color within the limitations of the intended printer’s color gamut has been a design skill for decades, since before digital editing even existed.