I'm applying for H4 visa and the process has changed need help ?

Set of questions asking for principle applicant details visa start date and end , reciept number and petitioner details.

My question is ,that principle applicant here is referred to H1 and in start date which start date should i mention

  1. Date mentioned in I797 or My Visa Approved date ?

  2. Now the complete process has changed if there is any sample link it would be helpful .

Thanks,
SSG

All the relevant details have to be as per I 797 petition while filling DS 160