Use the bag as warm up on your bench days (DE days if you max). That's kinda what I do, its a good way to get blood flowing and to fire up the CNS. Superset a round of bagwork with a set of pushups on off days do help with recovery from heavy bench days. Remember to go light, do not try and kill the bag. It cannot hit back. This is difficult for beginners. Try to keep your weight evenly distributed on your feet, the key to punching power is balance. Most of the power generated comes off the back leg (try not to lunge into the bag with your punch). Turn your hips into each punch, turn your shoulder/arm/fist over as you extend and connect at the end of your reach, with your arm almost fully extended. The more extended your arm is when you connect, the more speed you will have on your strike (force = mass x acceleration). Don't stand right in front of the bag. Circle around it. Put a song on and have fun with it, it doesn't have to be a grueling workout. Always wrap your hands. Don't forget to go to the body :).
As far as when to do this, is it alright to do it consecutive nights? I was thinking Fri/Sat/Sun since I work out 5 days a week, I can't really spend much time hitting the bag during the week .