It should be fine, there is no limit and, in fact, the more you drink, more probiotic you consume. Just be careful, if you are having lots of die-off, you may want to back off it a bit. I had to stop it few times during my treatment because hard die-off kicked in.
Kefir kills candida and other pathogens, this is why it is so beneficial during our treatment. It’s kind of antifungal and probiotic at the same time and both can cause die-off. That combined with other antifungals can kick off quite a lot of die-off.