I've prepared sweet potato puree mix with bm last night and store in fridge. Can i feed tonight? Im not sure if i am suppose to blend with bm first & store?

Yes, frozen purée can last up to a month by conservative standards. Just ensure that ur purée was stored in a container that u can use a lid / clean wrap to cover - some people prefer to put this set up in a ziplock bag too to extra ensure cleanliness. Just that u warm it up evenly and mix up any separated portions