If Nirvana is unconditional then why is it not happening now? It is said that Nirvana is unconditional i.e there are no conditions for it to happen. If so then why is Nirvana not happening now? Is my wish or suitability a condition for it happen?
If so then why is Nirvana not happening now? 


Nibbana is an existing reality. Its obscured by defilements just like a blue sky obscured by clouds. Insight-meditation and Jhana allows for the practitioner to experience and eventually attain Nibbana.


  Is my wish or suitability a condition for it happen?


A wholesome intention is the start but not enough in and of itself. It must be followed up by practice. We ourselves must do the work, ie. working for purification of body, mind and conduct.

I highly recommend reading the article "Nibbana", by Ven. Bhikkhu Bodhi.