How to extend eligibility period ?

my eligibility period is going to expire on June 30 and i want to extend it but confuse about process.
could you please how many days it would take? one guy told me me that if you sand a request to ecfmg for extension they will sent an letter to your college and your college have to send back this letter to ecfmg so it's take long time.
is it?? plz help:confused: