OPK test time when you work all day?

So everything I read says the optimum time to do the opk tests is early afternoon. I'm at work during that time and I share a bathroom with my only coworker, a guy. It seems like it'd be weird to have my pee cups and test strips there. Do those of you who use opks test at work? Or would I be ok doing them when I get home at around 6 pm? Thanks!