Reapplying for b2 how soon to reapply

[savithari]

Hello:

My parents have B2 till March 2011. They plan to visit us in May 2011 by which time their B2 would have expired.

How soon can they apply before the B2 expires ?

Can they apply in Jan/Feb so that they can purchase tickets and prepare themselves ?

Is there anything against them by applying in Jan//Feb before the expiry date of March 2011 ?

Regards,
-Savitha

[immihelp]

They can apply at any time.