Tall order for 8# weights.

While I want to honor your goals, my own approach is different: Do something. Anything. If it hurts, quit till it doesn't hurt any more. Don't do so much that it makes me want to quit.

The people in the magazines and videos with visibly cut muscles and the carefully-plotted food and rest schedules are using stacks of weights, not 8# dumbells (although they did start small).

Do a strength routine three days a week, and do your cardio when you can, and make sure you eat right, and in three months or so, look at how you feel and what you look like and hire a personal trainer. If you start getting persistently sore, make an adjustment or get a book and check your form.

You'll know what's going to work after the first two or three workouts. If 8# is kicking your butt, you won't be able to walk after the lunges. In that case, adjust the timing.

Good luck.