S.T.
a 5K is a good distance for an eight year old (still doing half years at this point??) and for you if you've been out of it for a while. your run/walk plan is a good one.
don't feel as if you have to push it super hard. a 3 minute run and 1 minute walk is fine too. and the 'run' can be a jog. it takes muscles and wind a while to build up.
don't expect your 8 year old to keep up with you. you're a young woman with long legs and experience in running. she shouldn't be starting out pushing it to the point of exhaustion. you can make your intervals even shorter- a one minute jog, 15 second sprint, another minute jog and one minute walk. you work up to sprints, you don't leap into 'em.
one of the best things you can do for both of you is to get really good shoes. i've tried a bunch and settled on altras. but don't skimp in this department. take it from someone who despite a lot of care got injured feet.
do your faster running without your daughter. i'm thrilled you're loving it again, but don't let your newly rediscovered joy leave her in the dust.
remember to stretch AFTER you run, and to warm up thoroughly and slowly.
happy running!
khairete
S.