It all depends on how your surgeon does your surgery and if he uses a brace or not. I tore my acl on January 8th of this year. Walked on it and skied once on it before my surgery February 8th. It's now almost 5 weeks after my surgery and I can stand all day, stairs dont bother me at all, full range of motion backward (cant straighten it the whole way, im about 10 degrees from knee locking).
The day of my surgery i had a nerve block so i was on crutches for just that day but i stood at my schools basketball game the whole time with a little pain. My surgeon uses a brace for the first 4 weeks that allows you to walk. I'm now in my third week of physical therapy but i wont be running again till the 3 month mark or any sports till the 6th month.