LC substitution question

[whatsnews]

Hi Guys,

I have questions regarding LC substitution.
I have an offer from a company which has approved
LC with job description matching with mine and
they are offering that they will do the labor substitution for me with the approved LC ( LC is not already used for I-140 )

I have got H1 receipt but still waiting for the approval.I have already started working for them.

I understand that LC substitution is possible
My questions are

1)I am assuming that LC substitution is filed with DOL and not INS. Please correct me if my assumption is wrong?

2)can I apply for LC substitution before H1 is approved?

2)If ans to 2) is Yes then Can I file I-140/I-485 before H1 approval?

Please guide me.

Thanks,

whatsnews