So, I have Bran in my deck. I add a plot card and then kneel bran to choose another. My question is, do the effects of the first plot take effect before I can Kneel Bran or not?

Yes, you can only use bran during a player action window. This means that you can use Bran's ability in the player action window before plots are played, or after plots are played. In either case you resolve all plots before anything else can happen. So you would get the when revealed effects from both plots.

Wheelz said:

There is an action window both before and after the standard framework of choosing a plot so you can choose when to trigger him. If both plots have WHEN REVEALED text, both effects are resolved. If you reveal a plot with a constant effect like Power of Arms however, that effect will get overwritten by any new plot you play.

The standard play is to use bran to reveal a plot with a good WHEN REVEALED effect, but bad initiative/income BEFORE the framework plot, then use the framework plot to reveal higher income/initiative.

Otherwise, you could reveal whatever during the standard FW action, then, once you know who the First Player is, reveal something like Search and Detain.

OK Cheers for the clarification.