Just a few thoughts
The key is to get the best UX Professional you can afford. I've interviewed and employed both rookies and experienced UX professionals over the years and the one thing that has always swayed it for me is how motivated they are - not toward the company but towards their profession.
What do they do in the spear time? What have they written about the subject? How does their work (even if it's limited) stand up?
A rookie will need support - can you or an experienced member of the team give it to them? If not (I personally believe) it's not fair on them at such an early stage in their career - unless they are super motivated.
With an established professional your organisation has the added benefit of being able to learn new things from their previous roles. Is your organisation receptive to that or do they have to be assimilated completely into your organisational culture?
(as said in previous answers) Interview both but do so with your eyes wide open about the level of support you need to commit to their on going learning and their commitment to change towards your organisation.