Another vote for "less than a week". I did one earlier this year and I think I remember it taking about 4 days.
"IF" you are in our "GROUP" of 4.00% NO FEE (PRIME + 0.00%)...YOU BETTER CONFIRM YOU STILL HAVE THAT OFFER!!! Mine expired WITH-OUT NOTICE!!! My last BT I did was 8.90% (all other previous BT'S are still 4.00%)