June visit

Hi,
I have 2 questions.
1. we are flying in June 2nd, how soon do we need to buy the JR pass, can we wait till April?

1. Once we get the JR pass, how do we go about making reservations for our trip to Kyoto and Osaka?
   Can we make these reservations without the JR pass now or do we need the JR pass first?

Thanks,
shomisaraj