Switching From L4 to F1. Need Help!

[acgent]

I'm currently living in U.S. with L4 visa and attending college. I'm turning 21 soon and my L4 visa expires. Once I turn 21, I will no longer be a dependent and have to apply for new visa to stay. I'm planning on finishing my undergrad and then applying to a master's program. How long does it take to get the visa approved after applying?
Also, I'm not really sure how different are the procedures than traditional F1 applicants, not residing in U.S.

[kabkaba]

What you will need to do is to apply for change of status while you are in the US. It can take 2 to 3 months for the processing. You will need some evidence that you have maintained residence in your home country. After that is approved, you can remain in the US in F1 status as long as you continuously maintain full-time student status towards a degree (and approved practical training).

If you leave the US at any point of time after that, you will need to obtain F1 Visa from a US Embassy/Consulate abroad. There is always a risk of denial in this application because of immigrant intent. Having parents in the US in L1 status makes it more risky for you.