I'd pre-wire for 7 speakers IF this will be your main A/V room. Since the Left, Right, Center are going to be within a 60° wedge, I would just run wire from receiver to speakers. I'd maybe put the bed headrest a couple of feet from the wall and wire ±150° for the back surrounds and wire ±90° for the surrounds. You can wire to the two front corners of the room for Front Height speakers for a total of 9 speakers.
If a simple bedroom 5.1 setup is your intention then I would wire the back two just as you have them in your diagram at ±90° to ±110° and put L/R on stands or towers at ±30° and center above or below TV. Wire the center in-wall if you plan on wall-mounting the center above the TV on shelf or "L" brackets.
Denon AVR X7200WA, Emotiva XPR-5, Emotiva XPA-7, Sony XBR 75" 850C, Oppo BDP-103D, Roku 4.
DefTech BP7000SC (L/R), CLR3000 (C), SM55 (FH), UIW BPZ/A (SB), UIW 75 (TM).
JBL L7 (Sur), EoSone RSR 350 (RH).
PC 2.1 setup. Emotiva Stealth 6, SVS SB2000 sub, Emotiva DC-1 DAC.