I eased into primal over 3 or 4 months, at first accidentally as I kept cutting back on grain and other processed foods as a way to reduce calories, and then more deliberately once I found MDA. I felt (feel) better and better all the time. Every little step has been an improvement. I'm probably 80+% diet-wise now, but I still feel like I'm easing into it. Some people prefer to just jump in the deep end, which is fine if that works for them. I haven't found that approach to be necessary. The other 20% is for convenience, pleasure, whatever and I don't stress over it. Over time, I imagine that 20% will continue to shrink.
As for non-primal family members, IMO, any SAD stuff that gets replaced with something primal is a good thing. My DH and kids (14 and 21) eat primal dinners when I cook, which is most of the time. They have what they want for breakfast and lunch, which is usually primal stuff plus whatever grains and grocery store condiments they think are necessary. DS drinks Coke and Gatorade, but I can see the volume is slowly decreasing. DD has been eating Honey Nut Cheerios with banana and organic milk for breakfast, but has recently asked for a bacon, egg and cheese sandwich. I am pleased about the reduction in sugar and dairy and will start with thinly sliced organic white bread while looking around for an alternative that she's happy with. I don't care if their transition is 10x slower than mine. It's better than not at all, IMO. It's easier for me than someone with vegetarians in the family, though, since mine are all big fans of meat.
CW-125, part calorie counting, part transition to primal
GW- Goals are no longer weight-related