I usually time it to around an oil change but it is not necessary.
Put bike into 1st gear
Remove the gear linkage bolt and
note the location of the punch mark on the shaft in relation to the slot in the linkageSlide linkage off the shaft
Remove the 5 screws on the cover
Remove the cover
Flatten the tab washer
Undo the Sprocket nut, If very tight get someone to press the rear break or use a piece of wood through the wheel on the swinging arm.
Loosen the rear wheel
Slacken off the chain adjusters.
Slacken of the nuts on the bar from Swinging arm to Caliper bracket (makes adjusting the chain much easier)
Lift out the sprocket (a bit fiddly)
Put new sprocket on the chain and a little bit of fiddling and turning to st the sprocket back on the shaft.
Replace the tab washer
Check if the nut is 9mm or 12mm thick, if 9mm replace it with this part number 90891-10124
If 12mm check the threads on the nut are ok, any doubt replace it.
Apply a little some blue loctite and Torque it up 80Nm using the same technique to tighten as loosening it.
Bend the tab washer onto the nut
Replace gasket if necessary
Replace Cover
Torque the 5 cover bolts to 10Nm
Slide the linkage back on in the same position of slot and punch mark when you removed it.
Tighten the bolt to 12Nm
Adjust the chain at its tightest spot. Good indication is if the chain can touch the wheel end of rubber swinging arm guard when pushed up then it is ok, if not it is to tight.
Tighten the axle nut to 117Nm
Finally tighten the nuts on the bar from Swinging arm to Caliper bracket to 23Nm
Take it for a spin
I think I covered it all