Before we get too far along into this build, and taking into consideration that this is a "first off", I thought it prudent to check the root rib fit against the fuse fillet. If there's going to be an issue, it's much better to find out before bits are glued together rather than after the fact... :-)
To perform this check one of the light ply root ribs was cut out of its panel. A sharp scalpel was used for this task. Take care not to damage the rib to jig tabs when removing parts from the panel. The wing tube hole and anti-rotation pin holes then had the waste removed from them.
To help define the edge of the fuse wing fillet, short pieces of masking tape with black pen marks were placed on the edge of the fillet in various places. See the photos. The fuse comes with holes for the anti-rotation pins and wing tube socket already cut but undersized to allow for adjustment. An appropriately sized drill bit was inserted through the root rib into the front anti-rotation pin hole to get things lined up. The two anti-rotation pin holes lined up perfectly and as you can see from the photos, there's plenty of room to the edge of the fillet allowing for the 2.5mm balsa sheeting. Actually, the sheeting should be 3/32" which is a fraction under 2.5mm. That should give me some sanding margin.