Yes, you can, as long as you know which agents are the new-hires.
Under Admin>Quality>Policies on the appropriate tab(s), select "Specific Agents", then start typing the name of an agent you want to add and select their name from the list that pops up.
Repeat for each new-hire.
Configure the other settings as desired (for example, set a Date Range to stop recording once an agent is no longer considered a "new-hire").