Since it's reactive to amine, I'm not sure if it will bind to any free amine group on the antibodies that bind to the surface receptors. I would test that if you have to do live/dead after surface stain before fixation. I have used another kit LIVE/DEAD™ Fixable Aqua Dead Cell Stain Kit that is also amine-reactive kit. I always use it before surface staining and stain in PBS for 10min at RT, then wash and do surface stain, and then fix my cells for intracellular staining.