I had H1B approved, but the COS denied from F1 to H1B and advised for consular service. If i file a MTR how long will it take if my H1 is is premium

First you need to determine the reason why your COS was denied.  Was it an error on CIS' part and an error in reveiwing your facts, or do you have a maintenance of status issue?  An approved H-1B but denied COS could mean that you have a serious maintenance of status issue. There is no premium processing for a MTR.  If you believe the CIS denial is an error and it is raised with the premium procesisng unit, the issue could be resolved in weeks.  An official MTR could take several months. The MTR does not provide any separate permission or status to remain in the U.S.  If you are no longer maintaining your F-1 status, you may need a different resolution than pursuing an MTR. Again, a denial of COS could mean you have a serious maintenance of status issue.  You may want to consider having an experienced immigration attorney review your matter to analyze any status issues.  Every case is different, and your specific facts would need to be analyzed to determine whether the denial of COS was proper. Regards, Andrew M. Wilson, Esq. Serotte Reich Wilson, LLP www.srwlawyers.com awilson@srwlawyers.com