You can start your internship at any time of the year, for a duration of 1 to 12 months.
You can arrive in the U.S. up to 30 days before the start of your internship. You can also extend your stay in the U.S. as a tourist for up to 30 days after the end of your internship. These two grace periods are to be used for tourism only.
Please note that your insurance dates correspond to your travel dates and not uniquely your internship dates.