What to do in the last week ?

If you are planning to take days off from studying, I would place it at the end of the studies just before the real exam instead of at the beginning of the week.

Also, see Prasanna's advice (which is the same advice I would give) on this post:

https://www.beatthegmat.com/query-on-tak ... 10084.html

If you haven't taken any GMATPrep cats up until now, I suggest taking one just to get used to the interface and difficulty progression because that's exactly what you'll see on the real GMAT.

There is another apsect of practice tests, which is the physical and mental training. I believe that last days practice tests are very important to help you become physically prepared for the GMAT.

However, I agree that the last 2-3 days need to be more relaxed. For example, I took the last day before the GMAT off, and went to an amusment park with my girlfriend. The day before that I went to the gym and studied more or less afterwards.

In conclusion, I think that the effort you put on the last prep week should look something like that:
G -7 ***
G -6 ****
G -5 ***
G - 4***
G -3 *****
G -2 **
G -1 *
GMAT Day


where one star is almost no effort at all, five stars are a full practice exam, its analysis and 20-30 questions in addition.