Supplementing until breast milk comes in..

My son was born on Monday he has been doing great with breast feeding but today It's like he's not getting satisfied. I gave him a little formula last night just to coat his tummy. He ate off my boob like 20 times today and poor guy still is not happy. Is it okay to supplement until i get my production coming in just so I know he's not starving?? My nipples are so raw I just needed the break. Makes me sad to see him upset and hungry