I was breastfed exclusively for a few months, then had some of each for a few months, then I was strictly bottle fed.
When my mother decided to have some of my feedings come from a bottle, my pediatrician recommended that she start with the late night / overnight feedings. As he put it, "That way, when she gets hungry at three o'clock in the morning, your husband can feed her and you can sleep."
If and when I have kids, I will do the same thing if I am able.