It's a very legitimate question since most of the H1-B applicants go through a similar waiting period in between the job offer and start working. However, in my humble opinion this question would have had a longer lifetime and better answers if you had posted in Quora.
I am in a similar situation with a joining date in next October. I decided to finish reading the books I never had time for reading, work on a few community projects and spend more time with my family. I hope it won't get too boring.