USCIS typically issues the EAD within 90 days of filing the application. It is a little late to be concerned with whether your employment is illegal or not considering you are currently working. Assuming you do not currently have employment authorization, your employment is illegal. An alien can only work in the United States with employment authorization.
However, your unlawful employment will be excused as you are seeking adjustment of status through a U.S. citizen. You must disclose your employment to USCIS. You cannot mislead USCIS about your employment as that can lead to more serious consequences.
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USCIS has 90 days from date of filing to issue an EAD.
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