Hi dreamworks,

I recently changed my status from h1 to f1. it took me around 41 days for the entire process. before changing my status I consulted with an attorney(shiela Murthy) she strictly advised on including 2-3 paystubb while filing COS. As there is no guarantee on whether the COS will be approved or not  depending on case by case but she gave me the probability 70-80% chances of getting approved with atleast 2 paystubb, 0% chance of getting approved without paystubb. and In case if it is rejected USCIS will send a letter to leave the country within 30 days. if you exceed this period(i.e u still remain in U.S) its considered unwanted stay and you'll have 3 yrs entry ban  if u stay illegal up 6 months you'll have 10 yrs entry ban if you stay illegal above 6 months but below 1 yr. and there is life long entry ban if you exceed over 1 yr after receiving notice to leave USA.

Also please file COS  atleast 60-70 days before the I-20 start date. who knows it might take longer than 40 days in u'r case. (Yes its true the website says COS might take upto 4 months). I hope this helps. good luck.