The information that you require is in the parts list & manuals area in question on lawnmowers.
The timing on a villiers (Atco) motor motor is usually 3/16" before top dead centre and the two arrows should be lined up. This is based on points setup not electronic ignition.
I hope that this is of some help.
Regards,
Bruce
Please do not PM me asking for support. Post on the forums as it helps all members not just the individual.