The reference is to notice of receipt of the application. It is not ordinarily recommended that people being working at a new job based upon the H1B receipt notice only, when that requires quitting an existing job or otherwise risking the loss of one's current status. The safest time to begin working for the new employer is after the new employer's petition has been approved. Waiting for an approval notice avoids the risks associated with leaving your current employer for the new job, but ultimately not obtaining H1B approval with the new employer.

Generally speaking you can return to work for a prior, approved employer. The transfer of itself does not revoke your right to return to any employer for whom you were approved to work under the visa.

We lack the information we would require to address your chances.