well there are a couple schools of thought out there.
I used to do Strength training 3 days a week, and Cardio 2 days.
MWF strength
T,TH Cardio
your body needs time to rest.
well after reading the book of "new Rules of Lifting" by Lou Schuler and Alwyn Cosgrove, I abandon my cardio routine all together for "awhile" at least, probably will restart a HIIT routine in May to go with the routines I am doing from the book.
But their recommendation as far as cardio was to do right after your strength exercise to reduce the chance of muscle reduction, as opposed to muscle breakdown and growth.
the experts on this board will want to know more about your stats, your goals your eating habits, all of that is part of it.
best of luck