E-file the I539 Change of Status petiton at USCIS website. I did it 1 month
ago to change from H1b/H4 to B2, and received an official receipt in 1 week.
My case is still pending. Currently the average processing time for such
petitions is 3 months. Hopefully I will have enough time to find a new job.
Good luck to me and to you!