Estes Black Brant XII, Kit # 9723 Build, Part 23, Assembly

I wouldn't recommend applying epoxy to the fin tab then sliding it into the slot. That would squeeze epoxy out into the fillet area. It'd be a mess to clean up.

I applied epoxy into the fin slot using a toothpick, then slid the fin into it.

A rubber band was used to apply pressure on the fin pushing it into the fin slot for a tighter fit.

You do have to check the alignment before the epoxy sets up. The rubber band can pull the fin to one side.

Glue in the fins one at a time only after the epoxy has set up.

The launch lugs are centered between two fins.

Looking from the lower lug - 

The upper lug segment has the balsa standoff. 

The Kevlar cord is slipped through the back end before gluing on the second stage orange tube.

You can see the epoxy glue inside the body tube right before it was slid in place.