CSAT - Only send one per day to a user

Hi - Hopefully a quick question

We have setup a customer survey to fire out 1 in every 10 incidents closed.

We're using the formula below to complete this but a question has been asked if we can limit this to only send one survey per day to the same user (some users can raise several incidents in one day ....) - anyone any ideas?

import System

static def GetAttributeValue(Incident):

Frequency = 10

is_divisible = false

if Incident.RaiseUser != null:

  if Incident.RaiseUser._DoNotSurvey == null:

   is_divisible = (Incident.Id % Frequency == 0)

  if Incident.RaiseUser._DoNotSurvey != null:

   if Incident.RaiseUser._DoNotSurvey.ToString() == 'False':

    is_divisible = (Incident.Id % Frequency == 0)

return is_divisible