How to file I-907 requesting PP pending H1B Extension?

Lawyer filed H1B Extension for me, RD 08/09 VSC. Does this Premium Processing request need to go through the lawyer?
I need the Approval Notice by middle of November. Then I need to submit this to get my Canada visa, for my flight end of Nov. I am worried that the processing only guarantee 15 days from the date of I-797 Notice Date. If it takes a couple of weeks for USCIS to issue Receipt Notice, my trip will be doomed anyhow.
Thank you for your advise.