I dont think there is a guideline in peak time or non peak time.
During business hour, usually most brothels doesnt line up as many girls compare to after hours, so you wont get many options as well.

But piece of advice, usually the pretty ones does not line up from 10am, they start around 2pm or 4pm, so you can take early mark around 3pm or 4pm and go visit.... thats when you have pretty one line up with the less prettier girls...