What should be the process of filling the ds-156 and ds-157 forms(For us H1-B visa)?

Question

When to fill these two forms before attending the embassy interview.

Answer 1

You can complete Forms DS-156 and DS-157 at anytime you wish, obviously before your interview, and you take them with you to the embassy on the day of your interview.

Answer 2

I would recommend seeking an attorney that specializes in immigration to help you prepare these forms.  Although it may cost quite a bit for the paperwork to be completed, it prevents you from having potentially costly mistakes later.