On June 4, Texas Service Center was processing change of status applications received on March 22, 2004. Check
http://www.lianglaw.com/INS/law-data/casestatus.htm
If you file an application right now, maybe you could get the approval before the end of August. Also you can do it yourself. Just file I-539 with required documents, like I-20.
A friend of mine filed the change of statue from H4 to F1 and got approved about one month.
Just for your reference, and good luck.