L1b to h1b l2 to h4 processing to remain in status

Hi, My situation: Currently on L1b expired. I94 expiry 2015 My wife : On l2 expired. I94 expiry 2015.ead expiry 2015. Employer A filing h1b for me. Wife’s employer filing for her h1b. Qn: in case of my wife’s h1b not getting selected and mine going through for processing: 1. Can I apply for her h4 once I come to know about the situation(after I get my receipt nunber) or do I need to do it now only? 2. Should I file for her h4 with my H1b only right now? Will that impact my wife’s h1b/ my h1b processing? Employer A tells me it might affect her processing.Better to do it after I get my receipt number. Thank You!