In short, you're good. JFBConnect v6.2.x already supports Graph API v2. Our extension is built in such a way that we will try to use Graph API v1.0, if available, since it's actually more flexible. However, when Facebook pulls that trigger in April and kills v1.0, we will seamlessly work with 2.0.
If you want to make the change now, you can go to the
Facebook Apps area
and then to Settings -> Migrations and enable the "Use Graph API v2.0 by default" migration setting.
I hope that helps,
Alex