Door Jamb gap blues

I'm installing a door jamb and need assistance. I've done my sums and I have a gap of 32mm beyond the door width and recommended 3mm space between door and frame. To address the gap, should I

1. Make wedges 16 mm each side or <O:p
2. Secure 16 mm plank the length of the door frame to the studs instead or
3. something else

I've started making wedges but they seem too thick and possibly won't give the door frame stability.

Interested to hear words of wisdom.

Secure 16 mm plank the length of the door frame to the studs is the best option

Unless your studs are very straight, you would be better to just use packers. Just use a bit of architrave docked about 90mm. Tack it in place one at the top, one at the bottom, one in the middle (or two if you are fussy) then fix your jamb stile, then use packers to get it plumb, do the same on the other side.