Did you get a TPLO or TTA?
I have a dog that has had 2 TPLO's...I would say 6-8 weeks. But then again this dog is a senior (10). Don't rush it, give it time to heal properly. Dog should be kennel bound and walked on a leash to eliminate. That's it for a while. You are probably past that point, but don't let the dog run around etc. until fully healed.
As far as slipping on the ice, definitely watch out for it. Don't take the dog in places like that. Shovel some snow, melt the ice with a propane tank torch (not salt, it hurts their pads).
Unit 23. Come in, 23. Do you need me out there? Do you need my assistance?