having good chakra control is not enough to control kurama's chakra,naruto was kurama's jinchuuriki all his life getting used to his chakra slowly,and tried to control his chakra most of his trip with jiraya,but he wasn't able to do it because neither him nor jiraya knew the right way to control a bijuu.Karin is good an chakra control.She can hide her chakra from oponent or sensor type.I am sure she will be able to control kurama chakra and use it to chakra boost or enchance her healing abilities
so saying karin after one day of recieving kurama's chakra(which is nowhere to be found)she will get accustomed to it right away is complete idiocy,controlling kurama's chakra is not like the MS you use it right away when you get sad,it takes hard work and time to do.