No. If you are breastfeeding it is best to breastfeed only. If you start using formula your body will stop making as much milk as it should. Formula companies honestly don't care what's best for your baby, they just want you to buy their products. It benefits them if your milk supply drops. Donate the formula to a food bank or a battered women's shelter so it will go to someone who needs it.
Two of my three kids never got formula (and I am proud to say that). My oldest did b/c it was prescribed when he was first born due to being jaundice. I too was sent formula- never really paid it too much attn and gave it way to friends who wanted it/could use it.