I've never been good at remembering to take my vitamins. I've always believed that if you eat healthy, you get your necessary vitamins, minerals and all around nutrients from your diet. What do you Paleo experts recommend? Do you take additional vitamins or supplements? I am still relatively new to this diet (day 5 - whoot! whoot!) ((btw, I have never actually said "whoot," but it felt right, so please forgive me lameness)).
If you eat fish, dairy and liver, then you are probably good with just Magnesium (chelate) and Vitamin D3 (as needed to stay at sufficiency, if you can't get enough from sun.)
If you've been a vegetarian for some time (like me), you may want to replenish your Zinc stores.
It's also a matter of the health of the soil used to grow the food. Small-scale farmers generally take better care of their soil's health. Factory farming, not so much.
Absolute need? Absolutely not.
Can they be useful? Possibly.
You will find that most paleo people on here are quite accepting of supplements that, well ... actually /supplement/ a healthy diet.
A mulitvitamin alone will not make you a healthy person. Incorporating specific vitamins (that you can read plenty of on here) and some food supplements (for e.g. if you are trying to gain mass and not lose), might be part of a modern, paleo-inspired lifestyle.
Disclaimer: I take some vitamins, and brewer's yeast & psyllium husks (within 15 minutes of waking up, before morning physical exercise).
There is no need. But SOME supplementation helps to act as a general buffer for those days when things don't go as planned, you miss meals, food forced on you at company gatherings, etc. As Dragonfly pointed out, modern supermarket foods don't quite have the nutrient profiles accessible to our paleo ancestors. The problems arise when people use supplements instead of eating healthy rather than as a supplement to eating healthy.
Perfect Health Diet and Primal Blueprint both recommend a good quality multivitamin as a good start. Several answers on here have recommended having a supply of Omega-3 oil on hand (fish oil, krill oil, cod liver oil, etc) and pop a couple doses after a meal heavy in Omega-6s. Primal Blueprint recommends a probiotic, Perfect Health Diet recommends getting your probiotics from food (it's your choice).
As for schedule, I find that it's just a matter of making it a regular habit, to the point where you just automatically grab your pills each morning -- ex. grab them before breakfast and set them next to your plate/bowl/mug/smoothie ...
Beyond that, eat healthy, keep an eye on your body (and PaleoHacks) and you'll be fine.