Level 2

ITIN to SSN update

My wife has received SSN, she previously had ITIN. I have sent request letter to IRS to 

void the ITIN and associate all prior tax information filed under the ITIN with the SSN.  Senn letter to: 

     Internal Revenue Service 
     Austin, TX [social security number removed] 


its been two weeks since i sent letter and there is no update from IRS. Just want to know how long it takes and how to track status of it?