Price floors update every day, typically between 1:00AM - 1:30AM PT.
Changes typically range between 5-20 Robux up or down in price.

At least one of the following: Bodies, Heads, Shoes, Hats, Hair, and/or Face are updated daily.
All other avatar item types are usually updated only on Tuesdays of each week.

It is not a guarantee that every avatar item type will receive a price floor change each day.