I'd be disinclined to describe what you'd notice as that might lead to you looking for those milestones in particular. Everyone is probably wired a little bit differently and may end up noticing different things. If one were given to drama, one could say that part of the practice is to sort of walk out into the wilderness and purposefully NOT bring a map, making exploration a part of the game.

To give you an example (with the disclaimer above in mind), I've a friend who noticed that he doesn't need as much sleep when he meditates regularly. Stop meditating, need for sleep increases. That's not the case for me, I need about the same amount of sleep regardless of amount of meditation. If I'd been told that less sleep is achievable, I might have been discouraged by the fact that this particular perk is nowhere to be seen for me. But I happen to know not to use another person's map for my personal wilderness.

For me, focus, patience, attention, memory and a very even (almost immutable, lately) temper are some of the things that have come out of this.

What's the difference between sitting with your eyes closed solving a puzzle and sitting at your computer figuring out how to solve a problem?

Quiescence is the whole point of the exercise. It requires a lot of discipline, which builds with practice, which is also the point of the exercise.

I certainly think that you could solve a puzzle and still have it down as meditation. In fact, that's sort of what a zen koan is. However, a koan would be designed to be tough to crack, but simple in structure (as opposed to complex). There's something to be said for learning to operate the brain in ways that are different to the sort of logical, problem solving kind of operational state that I'm sure many here (myself included) spend most of their time in. A koan is designed to make that part tired until it gives up. In that way, the inability to make progress with the puzzle itself is a design feature of a koan. But working on it produces a sort of meta-progress that has to do with the mind. Meditation is weird in that way, in that it's not about learning to play the piano, but learning to play the piano player. So to speak.

Also, boredom goes away eventually. Single minded, laser focus attention is one thing that this practice cultivates, and the kind of focus that I'm talking about is mutually exclusive with boredom.

Also, the shit your brain will make up and entertain you with once the chatter dies down is absolutely fascinating all in itself.

Find a time when you're naturally fairly calm. A lot of people like the morning right after waking up and getting ready. My preferred time is in the early afternoon.

There really isn't a specific time meditation should be done, you just need to find what works for you.

I'd advise against meditating shortly after having a meal, as it is harder to focus. Apart from that, pick a time that'll most likely work for you every day. Otherwise it's hard to build a habit.

I started out doing it between "coming home from work" and "having dinner", but that didn't really work out. Some days, I came really late and my GF was already waiting with dinner ready, other days I would go to meetup, hang out with friends etc.

I'm now doing Yoga and Meditation every morning after waking up, and there's just much less that can get in the way.

My GF and me are right now building an iOS app for forming a daily habit of Meditation and/or Yoga, based on our own experience and reading the book "Hooked: How to build habit-forming products". If you (or anyone else!) would like to beta-test, shoot me a mail at chris [at] screenscott.com :-)

Absolutely, this was not intended to be about semantics. The alternative interpretations were given so as to make it easier to dispel the cumbersome connotations that usually comes with the word "meditation", not to make it seem like it's about a particular school of thought or anything like that. It's just to make it easier to sit down and try it out with fewer preconceived notions as to what it's supposed to be.

I think it's the privilege of the practitioner to formulate what meditation is to them, and the easier it is to establish a personal relationship to the practice unhindered by baggage (cultural, institutional, linguistic or otherwise), the better.

Since we're discussing semantics here, "deep thought" is not something I'd think as mindfulness meditation either: you're not supposed to be chasing your thought while meditating. You should just be observing them as they come ("the intentional, accepting and non-judgmental focus of one's attention on the emotions, thoughts and sensations occurring in the present moment." as you said), and then let it pass by, which is pretty much actually the opposite of deep thought.