There are two ideal places in your house to do personal grooming, and unfortunately, they are never usually one and the same. These locations are in a bathtub or shower – for minimal mess that easily washes down the drain, and in front of a mirror (so you can see what you're doing). Most bathroom designs don't feature bath/shower spaces that are wholly visible in front of a mirror, however, because people don't really want to watch themselves wash.
So if the mountain won't go to Mohammad, Mohammad must go to the mountain. Take a mirror into the bath/shower area with you. Not just a small hand mirror, but, ideally, something larger you can set up nearby so you have access to both hands. Two hands are a lot more helpful than one when it comes to this stuff.
Alternatively, if you have complete (and I mean COMPLETE) privacy, you could always do your personal grooming outside. It's completely mess free as all epilated hair can just drop to the ground and get whisked away in the breeze. It's less gross than it sounds if you actually try it. Plus, your hair is an organic material and will happily break down in the environment.
What's important in personal grooming is never to leave a mess for anybody else. This is one of the more disgusting things a human can do to someone else who lives in there home. After using clippers, for example, tiny hairs fly everywhere. Not just in the immediate area but sometimes up the walls, all over and around the taps, and so on. This is why grooming in a bathtub is a good idea (particularly if there's a handheld shower head to wash it all off). When doing any kind of grooming where hair won't wash away, make sure you vacuum up afterwards, and wet areas will need a good spray and wipe.
Now for the question of when. Nobody has time for personal grooming before work on a weekday. Many of us ensure it's done before a night out on the town (not necessarily because anybody will see, but because it makes you feel confident). Sometimes we all get a bit lazy and let weeks go by without grooming at all.
The best answer to the "when" question is once a week, every week. This keeps maintenance time at a minimum. If you leave it for three weeks, it will seriously take three times as long. Saturday mornings or afternoons, I believe, are the best time for personal grooming – nobody's in a mad rush for the bathroom and it can be an easy time to get the house all to yourself. For optimal personal grooming, naturally, you need a good amount of personal space.