Question on topology

[KindPony (Pony)]

Hey, everybody! I need your advice on the topology.
How to make the same notch as on the reference

my option doesn’t seem very good

My models(Without my option)
gaming mouse-lowpoly.blend (816.8 KB)
UPD:Since I was misunderstood (my fault) I need to achieve this by Subdivision. Example:

I am not satisfied with my version because it has n-gon
gaming mouse-lowpoly-INTERSTING.blend (826.4 KB)

[LordoftheFleas]

Apply the mirror and bevel the central edge?

(+ some tweaking)
gaming mouse-lowpoly_1.blend (941.9 KB)

[KindPony (Pony)]

Sorry, my post misled you. It was only this morning that I realised it. It should be under Subdivision Surface

[ClintG]

gaming mouse-lowpoly-INTERSTING_2.blend (742.4 KB)

Quaded, how low poly has it got to be? it has slight shading issue in the fix, a few more poly could get rid

[KindPony (Pony)]

Cool! thank you