Can I start working with a new company after H1b visa transfer is filed

My h1b visa was filed in May 2012 and after RFE, I was denied visa. I appealed the decision and got my H1B approved with change of status from F1 to H1B on April 10 this year for a period of 3 years. I am being selected for an onsite interview by a company who is willing to sponsor my h1b visa. I wanted to know, how soon can I expect to work for this new company, if I get selected. Can I start working immediately after they file for transfer? Whats the typical time period for H1b transfer including the LCA time?

Once the LCA is processed (1-2 weeks processing time), the new employer can file for H-1 transfer. You can start working for them as soon as the petition reaches USCIS. However, most prefer to wait for receipt to be generated by USCIS to ensure that petition has successfully been accepted by USCIS. The downside is that in case H-1 transfer gets denied, then you will have to return to old employer or immediately file for another transfer. Go this route if you are confident about H-1 transfer approval.