H1B Upgrade to PP - Travel

I sent my h1b documentation for transfer from original employer to new employer on April 17th under the impression that it was filed as PP and finally found out the truth! So my attorney revealed that it was not PP and filed under regular process. I am in trouble as I need to travel abroad on May 20th! Now I am doubting my lawyer… - He said that he received the notification that a receipt was generated on May 1st but we will see the receipt in a few days. Is that possible, how did he find out that? Does USCIS send anything to the attorney when they accept the application? - Is there any way to upgrade to PP without the receipt, I doubt there is but want to be sure? - My lawyer says I can travel without a receipt or approved notification - I have quit my other job. I don’t think I should. What do I need to be able to travel. I have a valid stamped visa till 2017 from my old employer.