General rules of my thumb !
Anti-coll - whenever about to start engine to warns others and turned off on shutdown. Some places I've flown at leave the switch on so that it comes on with the battery master.
Nav lights - when the light is insufficient enough to need them...Noone is going to tell you off for having them on during the day but definitely at night as defined in the ANO.
Strobes - a little more difficult to say...maybe turned on during pre-take checks to show a little consideration for others on the ground. You might find you need to turn them off when IMC because of the reflection on the clouds.
That's my thumb ruled - anyone know any different ?