I seem to have run into a couple of different pieces of information regarding this, but I haven't seen a general consensus on it.

Is there one?

A guide I read said every 3 stacks.

But in a practice group for the fight the other tank detailed out to me you should do it at 1 or 2 stacks in the beginning, pending on the first phase jump, 2 stacks after that until the two Adds come out, and then 3 at that time because Provoke will be down from being use on add.

The above seems really dependent on knowing the timing of your group.

Also, don't tank swap right before a landslide.

tl;dr: Is there a standardized number of stacks you tank swap on Titan?