Hello Guys

I decided to pursue the CCDA certification,, first of all: do I HAVE TO take CCNA first?? I read in their site that there are no prerequisites to taking the 640-864 DESGN exam..
I don't have cisco experience,, I'm a system administrator with Windows Server experience,, though I once watched a video course preparing for CCNA..
Also,, I really don't have the luxury to study everything,, I can only find two or four hours daily to study... Can I prepare in two months?? if not, how much time is required??
I already obtained the official study guide of Bruno and Jordan..
Please Advice