Bloody hell. Replied to the wrong thread. Could someone please delete this?
I don't recommend it right before a tournament but rather a couple months before. It takes time to integrate a new concept or technique. I just got one in April from Brandon McCaghren and I'm still working with the concepts he showed me. Stuff is still evolving.
I try to do about every 6 months. They are a really good assessment point for me as I get to learn something new and drill it then roll with instructor and get a real time honest feedback on where I am at and the holes I need to work on. I also take my privates from places I don't train at so they don't know my game so the feedback is really good for me because they don't see me roll with other students they only know from our roll. Plus it helps build a great relationship with upper belts as the BJJ world is a very small one so good to have positive vibes out there. Hope this helps.