section B1 on SET(O) form

In section B1 of the SET(O) application form, is it O.K. if I just put the month and year that I started my degree? I can't remember the exact start date, and I can't remember what date I put when I completed my Tier 1 (General) extension application form.

Moreover, what do I list in the "grade" field? I attended university in the U.S. Do I put my grade point average?

For some other purpose with UKBA, I put "3.7/4.0 CGPA (USA)". Did not question me. However I did not pursue that line of application as my existing WP employer decided to retain me.

Start date - Month and year is OK.