Kenneth,
Because of the nature of the loan it is usually best to have a minimum of a conditional approval before locking. At that point the lender should be able to give you an idea of how soon they can close.
The best rate you will get is based on a 15 day lock term. If you know you are closing in that amount of time you should lock the rate. I hope this helps some. I would talk in more detail to your personal loan officer to get his knowledge of the situation and the specifics of locking. If you have more questions please feel free to contact me...
Sincerely,
Steve Smither
Ardain Mortgage
Senior Loan Originator
ssmither@ardain.com
847-942-5151 Cell
847-963-1000 Office - A few hours ago