H1 to F1 Change of status

[vivekasthana]

Dear Reader,
I have changed my status from H1B to F1 and my school starts on June 27th 2009. I got my Change of status(I539) approved and mailed out to me which has June as my start date of school. I am planning to differ my admission to fall semester due to medical emergency and that begins in the month of September. I was wondering if I could continue my stay in the united states legally between June until September or do I have to leave the country and reenter few days before the school starts?
I will appreciate someone's prompt response.

Thanks

[kabkaba]

No you cannot. In F1 status you have to be a full time student. You may take vacation only after completing 2 semesters.

[vivekasthana]

Thanks

But I am not taking any vacation. I am just differing my admission to next semester. I have not yet started school. I was on H1B until March'09 then applied for an MBA program and now my school is going to start next week and I dont want to start classes until next semester.
Just want to know if I could stay legally between now and Sep with the new I20.