I just had the same experience. File as soon as you can.
the letter from company is not necessary from my experience. However, you do have to do it as soon as you can. Theoretically, you are out of status the day you are laid off. The grace period is for your to prepare to leave the country or prepare the document to change to other status but has to be within a reasonable time (10 days, but I think it really depends on the person who process your case. Some lawyer would say 15 to 30 days). Usually even if the company report to INS your layoff, the INS won't process it untill two or three month later. So I suggest don't mention the exact layoff date because INS won't know at the time when they are processing your case. YOu can say "you are going to be laid off" and date your cover letter earlier and say that is your most recent pay stub don't say the last one).Good luck.
the letter from company is not necessary from my experience. However, you do have to do it as soon as you can. Theoretically, you are out of status the day you are laid off. The grace period is for your to prepare to leave the country or prepare the document to change to other status but has to be within a reasonable time (10 days, but I think it really depends on the person who process your case. Some lawyer would say 15 to 30 days). Usually even if the company report to INS your layoff, the INS won't process it untill two or three month later. So I suggest don't mention the exact layoff date because INS won't know at the time when they are processing your case. YOu can say "you are going to be laid off" and date your cover letter earlier and say that is your most recent pay stub don't say the last one).Good luck.