Should I lock or float my rate?
On a refinance transaction, if the savings you will achieve with the new lower rate will recapture the closing costs of the loan in a relatively short period of time, you should probably go ahead and lock your rate and close your loan.
Trying to time the bottom of an interest rate cycle is tricky and each month you delay costs you in the form of carrying a higher interest rate on your old loan. If rates fall further, you can always refinance again.
On purchase transactions, in times of stable interest rates, most of our customers lock when they are within 45-60 days of closing. Locking for a period longer than 30 days increases the cost of the loan slightly but is sometimes a good idea if rates are volatile.