If walking out, with a few safety precautions (ice picks, ropes, life jacket, floatation device, planks, fishing buddy, my mind went blank on what it’s called but the thing you jab in the ice in front of you) you can pretty much go right up until the ice has pulled away from shore and then some. Every situation and lake is different, but for the most part your north shorelines will go first. The main lake ice may still be a walkable for days or weeks longer depending on lake depth, sun angles, wind, rain, etc. While most people give it up when the ice is no longer drivable, some will go much longer. People may use wooden planks to cross a few feet from shore to the ice, or even waders or small boats. There’s not much that beats panfish ice fishing in 50 degrees in March or April. The fish are usually active, the fishing pressure is light, and the weather is great after a long winter.
I believe 2017 we were pretty much done by mid-late February. In 2018 we were still going mid-late April.