15 minutes daily isn't inherently wrong. And if you can recover from lifting AND from daily bagwork/skillwork, then by all means, hit it up every day. But personally, I'd suggest more like three, 30 minute sessions a week. Your oly lifting background should help you out with speed and power development once you get the skills down. But I think the repetition of skillwork is going to catch you by surprise - may only be a silly bodyweight movement, but throwing a jab 100 times (for example) still takes a toll on the muscles, which are going to need their rest. That's why I'd recommend a day or so between sessions, from the beginner standpoint anyway. Or your hands may even just need a rest from the abuse of pounding on the bag.
I say 30 minute sessions because for me, I need that much time to figure things out. If something isn't landing right, then I might spend ten minutes just focusing on that punch or kick. Later on when you really start to unload on the bag, you can cut the time down and into rounds. But I'd say that while you're still so green and trying to sharpen your technique, just take your time and focus on what needs to be improved. If one punch in a combination isn't coming out right, go ahead and work on that punch. Same as lifting, you don't just keep strengthening your strengths, you want and need to bring up your weaknesses.
Honestly, for every person on this forum that trains, you'll probably find a (at least slightly) different approach to bagwork.
Get some wraps and/or bag gloves. Be safe.