22 September 2011 is the date Episode 1 of Season 4 aired. (http://epguides.com/Mentalist/)
16 September 2011 is the date that Mentalist Writers said "Yes, Red John has been visible in prior Episodes. You've got to look for him like Waldo" (https://twitter.com/mentalistwriter/status/114530384280158208)

This means that we have actually seen RJ before season 4 started. We know that RJ is one of the seven names in the announced list.

First Apperances (Season x Episode)
--------------------------
Bob Kirkland 5x5
Brett Partridge 1x1
Ray Haffner 4x2
Reede Smith 5x1
Gale Bertram 3x1
Bret Stiles 2x20
Thomas McAllister 1x2

We have 4 suspects. Brett Partridge is dead, down to 3.

Sophie Miller says RJ is middle aged, and the priest that worked in barn backs this. Bret Stiles is out, down to 2.

RJ is either Gale Bertram or Thomas McAllister.

Story-wise, due to season 3 finale, I really think RJ should be Gale Bertram, but it seems like Thomas is Red John. When we look at Season 1, 2 and 3 as a whole, Thomas McAllister is the Waldo, not Bertram. Thomas is lost among many characters, and fits the statement perfectly.

I am really unhappy with this result, but taking the statements into account, Thomas McAllister is RJ. If RJ turns out to be Bertram, then the Waldo statement is wrong. If Bret Stiles is RJ, then we are fooled by Sophie Miller and priest. And if any other person is RJ, then we are fooled by official Mentalist twitter account, Heller and CBS.