I think your F1 changes to H1 automatically after Oct 1 if your H1 approval notice came with attached I-94 card (which means that your Change of Status or COS petition was also approved along with H1). Just to make sure, you can go to your school after Oct 1 and ask them to terminate your F1.
But from what you've written, I doubt that your COS was approved. I think you had already filed for H1 in April and got your new I-20 only in May after your OPT expired. If that's the case, I think your I-94 card didn't come with your H1 approval. If so, you have two options;
a) Ask your company to file COS ammendment petition with your new I-20. USCIS will process your COS from your current F1 to H1 and send you I-94 card. Advantage is you won't have to leave US for H1 stamping. Disadvantage is you don't know how long will it take and you can't work until it is approved.
b) Go out of US (Nepal, Canada, Mexico) and get the H1 stamping by Oct 10. I'm not sure about this 10 day regulation but had read somewhere that you need to get the stamp within 10 days of the start date.
If you can wait, I suggest trying to change status from F1 to H1 from within the US to avoid unnecessary visa complications outside US. First time visa stamping can be a little difficult in countries other than your home country. Hope this helps.
Good Luck!
Last edited: 15-Sep-07 04:25 PM