Only your ears will tell. Lately, I have been experimenting intensely with DIY panel traps and found that, in my room, one large trap (24" wide X 10' high 4" thick OC 705) was very beneficial, but when I added its mate to the opposite corner, the mid-bass was further improved but the room was (way) too dead. You can overdo it!
When I built a smaller one (same but only 12" wide), it provided a better balance of mid-bass attenuation without dampening things too much. Surprisingly, it did not affect imaging at all to have two different size traps.
The best thing to do is to buy a pack of OC 705 FRK (six 2" thick 2' X 4' sheets for about $135), peel the FRK facing off of half of them, cover each with cheap fabric sealed on the back with duct tape, and then experiment with different combinations of these in the corner to see what you like. When you find the right combo, build the frame and cover with the fabric you choose.
The 12" wide version may work for you in this corner if you like the effect of the additional treatment in the corner. If you don't like it, then make triangular echo traps with the 705 for the ceiling/wall corners. Also, definitely try them at first reflection points. Makes a big difference.
Good luck.