It depends. Most ac sprains (types 1, 2, 3) are treated effectively without surgery and athletes return to competition within 1-6 weeks depending injury severity. Types 2 and 3 result in mild to moderate prominence of the distal clavicle. A small percentage of types 1, 2, and 3 require surgery for persistent or late onset symptoms. Some type 3 and all severe (type 4, 5, 6) require early surgery.
Gradual improvement. Some of this depends on the severity of the separation most fall within the non-surgical realm though. Usually the first few weeks is fairly painful, then the pain should gradually subside and as it does would work mostly on shoulder mobility. Would avoid any lifting of substance involving the affected arm/shoulder.