This is a great question and I am sure that there will be a good amount of difference of opinion. I would say that it would really depend on a few factors. Let me explain.
First, if all the terminology is written down and given to the student, then I would expect the student to catch up much faster. After all, he or she has the information that he or she needs. If the student needs to learn through observation, then it will take much longer.
Second, the amount of terminology also makes a difference. The more terminology, the more time should be allotted.
Third, the frequency of meeting would be another important factor. If you meet everyday, then it will be easier for the student to learn. If you meet once a week, it will take longer. Based on these general considerations, you will be able to come up with a fair time frame.
In my opinion, if you meet at least a few times a week and you have a list of terminology, I would give three weeks. And during this time, I would give special attention to that student, so that he or she can catch up.