Transitioning to whole milk

My son is 14 months old and currently drinks breastmilk in his bottles for nap and bedtime. I stopped breastfeeding, including feeding to sleep around 12 months and ever since we have been giving him bottles he’s been sleeping through the night more often. I only have a few more small tubs of breastmilk left in the freezer which will last maybe a month and a half, 2 months at most. He drinks whole milk here and there, he won’t drink a full silly cup of whole milk though. He takes a few sips then wants nothing to do with it most of the time. My question is how can I get him to drink more of it? Especially for bottles before naps and bed time since he will no longer have breast milk?