Trading house from account A to account B will give account B the 7 day timer. The OLD house on account B will go into decay and display as slightly worn immediately, then its something like 5 days (someone can correct me if I'm wrong) until it collapses. The new house on account B will not be in decay and will refresh normally.
You should be fine to then trade the old house on account B to account A right away, which will give account A the 7 day timer and take the house out of decay.