Getting ready for PSM-1 certficiation

Hi Team,

I have gone through the Scrum guide, and have also read this book -
http://www.amazon.com/Agile-Softwar...with+scrum

Apart from this, I am now scoring 95-100% consistently in open assessment.
Can I go for the PSM-1 certification now?

Quick question, once I buy PSM-1 assessment, I understand that I can take as many attempts as I can but is there a timeframe in which I need to complete it?

Thanks
Girish