Exact steps and documents needed after ITA

Hi, I have a question. So I have overall 8 years of experience (2012-20)from which I’ve worked in the US for 2.5years (2017-19)with two different employers but I had some payment issues with my first employer (consultancy) so I transferred my h1b visa to my second employer (consultancy) and now my second employer is out of business since August 2019. So it is not possible for me to get a reference letter from either of those employers but I have both my h1b visa copies and pay stubs and also tax return documents that I filed. My question is can I provide the experience letters from India from 2012-16 will this do or it should be the most recent experience letters. Please help as I’m waiting for my ITA.

This is from personal experience -

if you have a colleague from any of those employers, it would be better to get a experience letter noting down job responsibilities and timelines, and notarizing the same.