Should I add vanilla before or after fermentation?

The carbon dioxide in the primary might drive off some of the volatile oils from the vanilla beans. You might want to do an extract with bourbon and then try mixing in small amounts into several small glasses just before bottling or kegging to get the ratio right. With vanilla sometimes less is more. The alcohol in the bourbon will get out more of the vanilla flavor. I'm not sure about with vanilla but I know with mead that often adding raw spices ends up tasting like crap and either cooking the spice first or extracting it mellows the flavor out.

 

You can add vanilla in secondary, but you should wait until fermentation is complete before moving to secondary. Or you could just add the vanilla at or near the end of attenuation and just leave it in the primary until the flavor is where you want it.

 

if you are going to secondary, there is no advantage to adding vanilla to the primary. none. there is also no advatage to adding the vanilla before fermentation is complete. as mentioned adding prior to FG could cause CO2 to drive off the volatile aromas, but vanilla is fairly robust.

most beers don't need to be put into a secondary, so there is that. but that is another conversation.
Cheers.

 

Your fermentation is, no doubt, finished after a week...Extracts and tinctures containing alcohol should be added after fermentation, I'd hang/bag the vanilla beans in the keg now if they haven't been soaking too long.

 

<sarcasm> It's a good thing you were there to measure the gravity for him. </sarcasm>

OP said his airlock is "bubbling away a decent rate." It's possible attenuation is not finished. He could have under pitched. Or he could be fermenting at a very low temperature. Or it could be a big beer. Or...

 

He didn't say it was an Imperial Porter and his avatar handle says "BrownaleGuy ( I missed the part about bubbling away at a decent rate)...certainly a gravity and more info would settle it.