F2 to H4 Visa transfer

My H1b Visa got approved today and the start date is today. My wife was in F2 status as I was in F1. I did not apply for her change of status to H4.
So now what are my options? How much time do I have before to apply for her change of status to H4?

Change of status can only be applied while the person have another valid status. In your case, because you didn’t apply for change of status for your wife to H4 along with your H1B, she is no more in F2 status. In fact she is now out of status starting the date your H1B is approved.

Best way to deal with this is go outside (preferably your home country) of the US and get H4 visa stamp using primary H1B approval and come back.

Consult your employer’s the immigration lawyer and they can guide you further.