It's not the unstable part that you're worried about, it's the efficacy of the product that you are ingesting. Creatine has to go through your first and second-pass metabolism. Now, it's very hard for it to do this when it is immediatetly mixed, and then ingested. If you start this process 30 minutes to an hour early, you are most likely going to send that creatine straight into the urinal. Why not put your creatine in a zip-lock bag? You can use printer paper as a funnel (it works great, my friends and I used to use this method on a pretty consistent basis), and send the creatin straight into the grape juice or water bottle, and shake until mixed. Then drink.