>>Do I fell each individual seam first OR do I sew all seams and then
>> fell everything at the same time?
the short answer--it depends.
You've already seen that finishing the shoulder seams before attaching
sleeves made sense.
If you are really set on sewing the side seams in one go, fell the side
gores seams first.
If you sew each bit of the side seam where seams may not match up so the
seam allowances are not caught, then you can fell afterwards.
As with so much in reenactment, there is no one true way.
Ann in CT