how many days in advance we can arrive USA on H1B after 1st Oct


I am in US and working on H1B visa. My wife is in INDIA and got H1B visa stamped.

Her employment start date in US is 15th April 2014.

Is it OK if she comes to US on H1B now and start working from 15th April 2014?

If it is not allowed, how many days before she is allowed to enter before her start date.

Is there any other options available (get the H4 done based on my H1B enter US and then before joining here applying for COS from H4 to H1B).

Is the above process is simple or very complex. 

When we apply from H4 to H1B does she come under cap exempt?

Thanks in advance

She cannot enter US on H-1 until she plans to start working on H-1 immediately. If the employer is ready to start employer early, then she can enter as per that new date.

Yes, she can enter on H-4 and then file COS from H-4 to H-1 later. In this case, she cannot start to work on H-1 until COS gets approved. Also, when she appears for H-4 interview, there is a possibility that her H-1 visa stamp is canceled w/o prejudice.

H-4 to H-1 will be cap-exempt as she has already been counted in the cap.