Sprained my ankle ~5 hrs ago. its swollen and feels stiff. had it elevated for atleast 3 hours and have been icing it. when should i start stretching?

Ankle Sprain: See your doctor first and have an X-ray if needed. Not all ankle sprains are equal, and they sometimes mimic an ankle fracture. Syndesmosis injuries ("high ankle sprains") require much different treatment and sometimes surgery. Lateral sprains are the most common and only require surgery for very severe injuries, but can mimic fractures of the ankle. PT for strengthening and proprioception ASAP.

A real pain in the..: Don't even consider beginning stretching exercises until after the initial pain and swelling has gone down. After weight bearing is tolerable would be the best time to start stretching. This could be a little as 5-7 days for low-grade sprains and considerable more for more severe sprains. Sprains come in various degrees of severity and a professional evaluation is probably the best starting point