It depends on your personal finances. We have excellent credit and money in the bank and it still went back and forth to underwriting several times. We had to prove, prove, and reprove that we own several properties free and clear. Apparently, people claim to own property free and clear and then have private loans against them. Then, our current mortgage sold to a different lender in the process so we had to prove that it was for the same rental property and not another loan - this involved third party verfication via a credit supplement which added two days. That same mortgage lender ran a SP on our credit so we had to write a letter of explanation - add another two days. In our case, it was about two weeks of back and forth. However, we have also have had deals that finish underwriting in less than 72 hours. The more layers that you have, the longer it will take. It also depends on how responsive the mortgage broker and underwriter are in getting back to each other.
http://ficoforums.myfico.com/t5/image/serverpage/image-id/2760iB9166C1A493A3CBC/
Starting Score: 547 May 2013 to 698 December 2015 
