will an alert get created right away or as per damper settings?
It will be created at the first occurrence of the trigger condition and then again after the end of the damper period. If you have a damper period of 20 minutes, you'll get alerts at once and then after 20 minutes.
For some notification conditions, you can disable the damper, however that does not apply to the "Virus definitions out-of-date" condition. For this notification the shortest damper period is 20 minutes.