L1 to H1 lead time

[txh1b]

So I am continuing with my present L1 with employer XYZ till company ABC finds a proper oppurtunity in H1 .

ILLEGAL

[orion]

1. Illegal if it was a COS.
2. And if it was, you are already OOS.

3. Read a GAZILLION posts on similar issue.

[vijay_ambhika]

Hi

I am currently in L1 with an employer (XYZ) working since Apr 2008. Before arriving to U.S, I also had H1B stamped. So during Aug 2008, I applied for change of status from L1 to H1 thru another employer (ABC) in a premium processing. As a result of premium processing my H1B transfer got approved quickly in a month time and I currently have both H1 and L1. My new employer ABC is asking me to wait till economy gets better. So I am continuing with my present L1 with employer XYZ till company ABC finds a proper oppurtunity in H1 . My question is:

1. is it legal to work in L1 after getting H1 approval?
2. If so what is the lead time given by USCIS in which I shall shift from L1 to H1?

Please provide your suggestion.

Thanks