M.6.
We took our poodle in twice before she turned 9 months old for "limping" that had no obvious cause. She didn't seem to be in pain or anything. Both times, we took her to the vet and both times told the same thing: "she pulled something playing - this is very common in puppies, especially poodles." Both times they sent me home with a mild pain killer (which was more for me than my puppy). I will say that my poodle has a very high pain tolerance and doesn't cry or whimper when she is in pain.
If the limping is the ONLY symptom, I think I would be ok waiting. In fact, I think I would give it 48 hrs before going in anyways and instead of an xray, just ask for an evaluation.
Our poodle is now just over a year old and we love her to death!!!!!