Gusset length

[Danotriglide]

Trying here too…

I posted this question in How To but no one’s stepping up. 
I’m making a bag 9”x5-3/4” of 2mm thickness leather. I’m stitching by hand and have layed out and punched the holes about 3/16” from the edge. The 4 corners have 1” radius. My search here came up blank so I’m asking…do I add all sides together and subtract the circumference of the 2” diameter or work from the dimensions of the sewing line? I tried the old string around the outside all the way around and the string layer over the sewing line. Outside strings 1-1/8” longer. I’d like to learn how to get it right the first time and not trim it to fit or piece it together. 
 

Thanks!

Dano

PS

I’m laying the outside panel on top of the gusset.

[Dwight]

Do it however you want . . . but if my project requires a gusset . . . I lay down the item . . . trace the outside for the length of the gusset I want . . . then cut the outside of the gusset piece out of a hunk of leather.

I then decide how wide a gusset I want . . . use a pair of dividers and mark that all around the inside of the piece I cut out 

I then cut out the gussett . . . glue it in place . . . sew  /  lace / stitch /  as necessary.

May God bless,

Dwight