staining - How long does it take to stain cells?

For fluorescence immunocytochemistry, there are 3 main incubations that determine duration of the procedure. Generally it takes 2 days to stain your cells before you can visualize them. Once cells or tissue are fixed onto glass, you first incubate with a primary antibody to directly target a specific antigen(s), usually overnight. After primary labelling, a secondary antibody is applied to target the primary antibody, which usually takes a few hours. These secondary antibodies come conjugated to some fluorescent dye (Cy5, TRITC, FITC, AlexaFluors, etc). A nuclear counterstain is really quick, only 5 minutes. After all the labelling and nuclear stain, you can mount the coverslip with mounting media and once it cures you can visualize them.

Abcam has one of many quick reference guides.