It should be ok to do so after the first day.  Yes, it is OK to take your dog go up and down the stairs with a controlled leash after the first day of surgery. But make sure you take them slowly and discourage running or any rough behavior. The first few days after your dog is being spayed are critical, and you need to take utmost care of your dog. Give your dog love and affection, and get him to chew toys to keep them calm and safe.