Google PR effect on domain name change?

Hi,

Today, we have changed the domain name of yezhuththu.com to eluthu.com - following Google's guidelines. We had a PR of 3 for yezhuththu, we used 301 redirection, let me know how long it would take to retain our PR and AR back.

I think it will take about a month minimum, for maximum it could take 2-3 months.