She may come into heat any time now. Typically most dogs have their first heat cycle at age 8-12 months but can come into heat as early as 6 months. I just spayed an 8 month old dog today that just finished her first heat cycle.
Usually around the age she is now you will know when and then you can give her asprin for cramps. They are just like us they get cramps too!! Best of luck to you !!!!!