I would suggest that you drill and rivet it when you are fitting the canopy side skirts to be flush with the skin and after the rivets to the side rail are done. Be sure all is in the right position with respect to the canopy contour and the roll bar. For me, the contour of the frame was deceiving and I only knew what the true width was after clecoing both the side skirts on. It becomes very stiff once riveted and does not bend easily. Actually, I had the canopy on it and pulled the frame up to the canopy as it sat on the roll bar. Snugged it all the way around and aligned the skirts. This is the "drill in place" way to ensure a good fit.
You might (will) want to cleo a long angle across it to hold that width in place, as it can not be riveted in place on the fuse, not adjusted easily after riveting.
Good luck, this canopy frame fitting develops a lot of skills. It is not forgiving of early mistakes. Cleo 5 steps forward and go 4 steps back to drill/rivet. This might be an understatement.
