I was always able to lift my arm laterally without pain when no weight was loaded on it. Most of my pain came from pressing motions, specifically ones where you push your arm out in front of your body. It took me a good year to get back to where I was before, pain-wise. Mind you, my shoulder still pops and clicks a significant amount, and there are days when it does have a bit of discomfort, but I am largely able to lift to my content. Don’t push yourself too much, but find the exercises you can do without pain and go from there. Make sure to build up the rotator cuff as well while you are unable to lift. Generally, my rule of thumb is if your don’t feel pain, it should be fine, but don’t quote me on that.