Wait until ADSAccount is created


I have a process that calaculate and update an attribute in ADSAccounts based on Busienss Roles.

When the process is triggered, i want :

1- check if an ADSAcount already exist (even disabled)

   if yes, then compute the new value of attribute

 if no, wait until and ADSAccount is inserted (given by the Business roles, but takes up to 30 seconds)

So i want to implement this in a process : Wait until an ADSAccount is inserted

Any isea which component can provide this possibility?

Thank you by advance