Green Card application process and duration

[bnb_india]

Hi,

I am on H1b visa and I want to apply for green card with my current employer. I don't want to stick to current employer too long. I know that there are different stages of the process but I am not aware of all the stages and the whole process. So can you please tell me

1) What is the process for green card application?

2) How long it takes to get green card or to clear different stages?

3) When can I change my employer? Erliest and safest without sacrificing my green card application?

Thank you.