186DE employment contract

I found an employer willing to sponsor me.
Different company to the one I currently work at.
Employer agreed that I can start work after 186 grant.

Will it affect my file?
Is it okay to have employment contract that says start date is after visa grant?

Wouldn't the visa officer ask that if I'm onshore and not yet working with employer for nearly over year given the processing then is it a genuine job?

Is anybody else in same situation?
What did you do?