File immediately, it can take 3 months to process.
Read the instructions closely regarding fees.
PROFESSOR OF IMMIGRATION LAW for over 10 years -- This blog posting is offered for informational purposes only. It does not constitute an attorney-client relationship. Also, keep in mind that this is an INTERNET BLOG. You should not rely on anything you read here to make decisions which impact on your life. Meet with an attorney, via Skype, or in person, to obtain competent personal and professional guidance.
It is appropriate to file 90 days in advance because it takes that long to process your application.
The information you obtain from this response is not legal advice. You should consult a qualified attorney for advice regarding your individual case and situation. This response does not create an attorney-client relationship of any kind.