In years past you could not start accumulating CE credits for your next recertification period until after your last recertification period had ended, so after July 31 of your recertification year. NBCRNA recertification rules have changed a bit. Now the NBCRNA says that once your recertification has been approved you can start earning CE credits for your next recertification period. For example, say your recertification deadline is July 31, 2014. Once you have completed the recertification process for this year you can start earning CE that will count towards your 2016 recertification.
Here is a quote from the NBCRNA web site: "For example, an individual whose 2014 recertification application is approved on April 18, 2014 may start to earn credits for their 2016 recertification cycle the following day, April 19."
So, if you recertify early, once you've received your approval from the NBCRNA you may start earning CE credits that will count towards your next recertification period. This might be a reason to recertify early if you have CE money you want to spend right away or there is a meeting you really want to go to this summer but you already have all the CE you need to recertify this year.