I haven't worked with an active strain of floribunda yet but I have tested a lot of the commercial varieties around melbourne with no success. this one which I recently photographed and plan on testing very soon has all the characteristic your looking for and i strongly suspect it is active... the pic is during flowering.. but basically whenever its not flowering is preferable. summer is reccomended.. so around now

Acacia photo gallery - The Ethnobotanical Garden - Welcome to the DMT-Nexus notice the very white flowers as opposed to the creamier yellow flowers you see in most commercial varieties around melbourne