Im a full contact kickboxer and have had about 2 fights having my 3rd 1 in june and i want to get into mma?

im a full contact kickboxer and have had about 2 fights having my 3rd 1 in june and i want to get into mma i have started brazilan ju jitsu today and want to get into my first cage fight by next christmas how long do you think it will take me to get hold of the ground game because my stand up is alright i just started grappling!