Yes, they lag. If you're looking for a mortgage you should be pulling your fico scores anyways to get ready and those come with the reports to verify.
Since the TU rep claimed it was added, that means they can prob see it on your report. You can check your TU report on their website (transunion.com) - their free service allows daily report pulls & will have the most up-to-date TU data.
Or, go to https://www.annualcreditreport.com/index.action and get your free reports from all three bureaus. This is the only federally mandated site for obtaining a free credit report (reports only, no scores). -- the reports received will be more comprehensive; you can confirm if the account has reported to all 3 bureaus.
+1 for getting your FICO mortgage scores as suggested by previous poster.
So on Credit Karma...
We are trying to get pre approved for a house.....
If you're thinking of buying a house, Credit Karma is not where you should be looking . Get your actual FICO scores and not CK's Vantage scores.
Why are you not talking to the lender directly? Many people make the mistake of getting Ficos scores that may not get pulled by the lenders, they use a Tri-merge report, which may have different scores. Get pre-approved with your lender 1st, they dont pull credit on the 1st meeting, they will gather information and ask for documents. Its a process and when they give you a number, you work with your realtor to help you find a home with you. A good lender and realtor will help smooth out the process for you, just give them what they ask for and that wont delay the escrow closing, when you find that home.