At the time of answering this question (Dec 2014), the next time will be in 2025.
Easter Saturday will next fall on April 12 in 2031.
The next time May 21st falls on a saturday is in 2016.
in 2021
2015
2021
As of 2017, it will be in 2018 and the next time after that will be in 2029.
The next time October 31 falls on a Saturday is in 2015.
May 23 fell on a Saturday in 2009 and will again fall on a Saturday in 2015.
The calendar repeats every 11 years. Therefore - the next time April 20th will fall on a Saturday is 2024.
2017.
After 2011, when the question was originally asked, the answer was 2015. The next time after 2015 is 2026.
The next time that April 16th falls on a Friday is 2021.