Buff, just take it one day and one week at a time and do it at your own pace. I obviously wasn't ready to cut out all 3 sessions and needed to hang on to one session while I adjusted to the idea of not being a pumping mom during the day. After almost 2 months of pumping once a day it was easier to drop that last session and I was ready.
As for the transition to cow's milk, you may have to try different temperatures in addition to mixing it with formula or BM. But if your lO gets enough other dairy (yogurt, cheese, etc) then you don't even have to offer cow's milk.