In short, yes it is ok. You would have to ingest a large amount of caffeine (which by itself would be harmful) to see any protein inhibition. However, I do have some advice for you. Don't drink protein before your workout. Protein repairs your tissue and can act as carrier molecules, but are rarely used as energy (only about 5% of your daily energy output originates from protein). What you need before (and after) your workouts are carbohydrates. Drink your protein shake late in the day or close before you go to bed. You do most tissue repair at night, so that is when you need it most.