I think you bought more than what you strictly need for a successful treatment of acne scars, but never mind.
From our experience, a combination of a dermastamp and a dermaroller was more successful in treating scars than a dermaroller alone so I suggest you include the dermastamp and/or the single needles in each session.
If you have lots of scars, spread out the treatment so that you can do it thoroughly and densely. During the same session, stamp the scars of one cheek (and the temple for example) with your 2 mm dermastamp and then roll the entire cheek with your 1.5 mm dermaroller. Keep the treated area moisturized until it heals. Do not fully insert the needles of your 2 mm dermastamp in the temple area because the skin is relatively thin there. Insert just the tips. When it heals, treat the other cheek etc.
You can use your 0.2 and your 0.5 mm dermarollers in between your sessions, with the gaps you planned. Frequent rolling with shorter needles is especially useful for acne prone skin, post acne pigmentations or other uneven skin tone problems.
When your 1.5 mm dermaroller gets blunt and when you are experienced with dermarolling, you can replace the 1.5 mm one with your 2 mm dermaroller (when you roll the temples, do not push the needles in).
Prior to your session, try the 2 mm dermastamp on a small area of your face to see how it reacts and how it heals.